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Princeton Review MCAT Biology Glossary
Terms in this set (820)
A methylated guanine nucleotide added to the 5' end of the eukaryotic mRNA.
necessary to initiate translation of the mRNA.
4.7 and 4.8
The band of the sarcomere that extends the full length of the thick filament.
includes regions of thick and thin filament overlap, as well as a region of thick filament only.
alternate with I bands to give skeletal and cardiac muscle tissue a striated appearance.
does not shorten during muscle contraction.
absolute refractory period
A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation
The minimum stimulus intensity required to activate a sensory receptor 50% of the time.
The three glands in the male reproductive system that produce semen: the seminal vesicles, the prostate, and the bulbourethal glands.
1. In the GI tract, organs that play a role in digestion, but are not directly part of the alimentary canal.
• salivary glands.
2. In the reproductive systems, any organ involved in reproduction that is not a gonad (testis or ovary).
The neurotransmitter used throughout the parasympathetic nervous system as well as the neuromuscular junction
enzyme that breaks down acetylcholine in the synaptic cleft
Enzymes that degrade various macromolecules and that require an acidic pH to function properly.
found within the lysosomes of cells.
Cells that make up exocrine glands, and that secrete their products into ducts.
For example, in the pancreas, acinar cells secrete digestive enzymes; in the salivary glands, acinar cells secrete saliva.
A region at the head of the sperm cell that contains digestive enzymes which, when released during the acrosome reaction, can facilitate penetration fo the corona radiata of the oocyte and fertilization
13.2 and 13.9
A contractile protein. In skeletal and cardiac muscle, actin polymerizes (along with other proteins) to form the thin filaments.
involved in many contractile activities, such as cytokinesis. pseudopod formation, and muscle contraction.
6.5 and 11.2
A localized change in a neuron's or muscle cell's membrane potential that can propagate itself away from its point of origin.
all-or-none process mediated by the opening of voltage-gated Na+ and K+ channels when the membrane is brought to threshold potential; opening of the Na+ channels causes a characteristic depolarization, while opening of the K+ channels re-polarizes the membrane.
Proteins that bind to enhancer sequences in eukaryotes to increase transcription.
The movement of molecules through the plasma membrane against their concentration gradients.
requires input of cellular energy, often in the form of ATP.
An example is the Na+/K+ ATPase in the plasma membranes of all cells.
1 of 4 aromatic bases found in DNA and RNA;
also a component of ATP, NADH, and FADH2.
purine; and pairs with thymine (in DNA) and with uracil (in RNA).
anterior pituitary gland
The inner region of the adrenal gland.
part of the sympathetic nervous system, and releases epinephrine (adrenaline) and norepinephrine into the blood when stimulated. These hormones augment and prolong the effects of sympathetic stimulation in the body.
A constant nervous input to the arteries that keeps them somewhat constricted to maintain a basal level of blood pressure
adrenocorticotropic hormone (ACTH)
A tropic hormone produced by the anterior pituitary gland
targets the adrenal cortex, stimulating it to release cortisol and aldosterone
The small artery that carries blood toward the capillaries of the glomerulus
A neuron that carries information (action potentials) to the central nervous system;
a sensory neuron.
A blood protein produced by the liver.
helps to maintain blood osmotic pressure (oncotic pressure).
The principal mineralocorticoid secreted by the adrenal cortex.
steroid hormone that targets the kidney tubules and increases renal absorption of sodium.
AKA gastrointestinal (GI) tract or the digestive tract
long muscular "tube" that includes the mouth, esophagus, stomach, small intestine, and large intestine
A version of a gene.
For example, the gene may be for eye color, and the alleles include those for brown eyes, those for blue eyes, those for green eyes, etc.
At most, diploid organisms can possess only two alleles for a given gene, one on each of the two homologous chromosomes.
(Singular alveolus) Tiny sacs, with walls only a single cell thick, found at the end of the respiratory bronchiole tree.
sites of the gas exchange in the respiratory system.
The building blocks (monomers) of proteins.
There are 20 different amino acids.
amino acid acceptor site
The 3' end of a tRNA molecule that binds an amino acid. The nucleotide sequence at this end is CCA.
amino acid activation
see "tRNA loading."
A tRNA with an amino acid attached.
made by an aminocyl-tRNA synthetase, an enzyme that is specific to the amino acid being attached.
A sac filled with fluid (amniotic fluid) that surrounds and protects a developing embryo.
An enzyme that digest starch into disaccharides.
secreted by salivary glands and by the pancreas.
The process of building complex structure out of simpler precursors( e.g, synthesizing proteins from amino acids)
Physical structures in two different organisms that have functional similarity due to their evolution in a common environment, but that have different underlying structure.
arise from convergent evolution. (similar environmental pressures)
The valve that controls the release of feces from the rectum.
has an internal part made of smooth muscle (involuntary) and an external part made of skeletal muscle (voluntary)
3rd phase of mitosis.
replicated chromosomes are split apart at their centromeres (the sister chromatids are separated from each other) and moved to opposite sides of the cell.
3rd phase of meiosis 1.
replicated homologous chromosomes are separated (the tetrad is split apart) and pulled to opposite sides of the cells.
3rd phase of meiosis 2.
sister chromatids are finally separated at their centromeres and pulled to opposite sides of the cell.
identical to mitotic anaphase, except that the number of chromosomes was reduced by half during meiosis 1.
Male sex hormones.
Testosterone is the primary androgen.
Immune system cells that become unresponsive but do not go through apoptosis
e.g. B cells and T cells that recognize self-antigens.
A normal blood protein produced by the liver,
converted to angiotensin 1 by renin (secreted by the kidney when blood pressure falls)
further converted to angiotensin 2 by ACE (angiotensin converting enzyme)
Angiotensin 2 is a powerful systemic vasoconstrictor and stimulator of aldosterone release, both of which result in an increase in blood pressure.
something that acts to oppose the action of something else.
For example, muscles that move a joint in opposite direction are said to be antagonists.
anterior pituitory gland
made of glandular tissue.
makes and secretes six different hormones:
controlled by releasing and inhibiting factors from the hypothalamus.
proteins secreted by activated B-cells (plasma cells) that bind in a highly specific manner to foreign proteins (such as those found on the surface of pathogens or transplanted tissues)
The foreign proteins are called antigens.
Antibodies generally do not destroy antigens directly, rather, they mark them for destruction through other methods, and can inactivate antigens by clumping them together or by covering necessary active sites.
A sequence of three nucleotides (found in the anticodon loop of tRNA) that is complementary to a specific codon in mRNA.
The codon to which the anticodon is complementary specifies the amino acid that is carried that tRNA.
antidiuretic hormone (ADH)
produced in the hypothalamus
secreted by the posterior pituitary gland
targets the kidney tubules, increasing their permeability to water, and thus increasing water retention by the body.
A molecule (usually a protein) capable of initiating an immune response (antibody production)
Cells that possess MHC II (B cells and macrophages)
able to display bits of ingested antigen on their surface in order to activate T cells.
see also "MHC"
A carrier protein that transports two molecules across the plasma membrane in opposite directions.
largest artery in the body
carries oxygenated blood away from the left ventricle of the heart.
Programmed cell death due to eternal stressors such as toxins or internal signals such as an increase in the product of tumor suppressor gene.
mediated by a family of proteins called caspases.
A mass of lymphatic tissue at the beginning of the large intestine that helps trap ingested pathogens.
A thin, watery fluid found in the anterior segment of the eye (between the lens and the cornea).
constantly produced and drained, and helps to bring nutrients to the lens and cornea, as well as to remove metabolic wastes.
A function in the reproductive system, controlled by the parasympathetic nervous system, that includes erection (via dilation of erectile arteries) and lubrication.
A blood vessel that carries blood away from the heart chambers.
has muscular walls to regulate blood flow and are typically high-pressure vessels.
the site on a ribosome where a new amino acid is added to a growing peptide.
atrioventricular (AV) bundle
AKA bundle of His
first portion of the cardiac conduction system after the AV node.
atrioventricular (AV) node
second major node of the cardiac conduction system (after the SA node).
The cardiac impulse is delayed sightly at the AV node, allowing the ventricles to contract just after the atria contract.
The valves in the heart that separate the atria from the ventricles.
The tricuspid valve separates the right atrium from the right ventricle
The bicuspid (or mitral) valve separates the left atrium from the left ventricle.
These valves close at the beginning of systole, preventing the back flow of blood from ventricles to atria, and producing the first heart sound.
One of two small chambers in the heart that receive blood and pass it on the ventricles.
The right atrium receives de-oxygenated blood from the body through the superior and inferior vena cava
the left atrium receives oxygenated blood from the lungs through the pulmonary veins.
The first step in viral infection.
Attachment of a virus to its host is very specific and is also known as adsorption.
AKA the Eustachian tube
The tube that connects the middle ear cavity with the pharynx
Its function is to equalize middle ear pressure with atmospheric pressure so that pressure is equal on both sides of the tympanic membrane.
An immune reaction directed against normal (necessary) cells.
For example, type 1 diabetes mellitus is an autoimmune reaction directed against the B cells of the pancreas (destroying them and preventing insulin secretion), and against insulin itself.
autonomic nervous system (ANS)
AKA involuntary nervous system
The division of the peripheral nervous system that innervates and controls the visceral organs (everything but the skeletal muscles)
can be subdivided into the sympathetic and parasympathetic divisions.
An organism that can makes its own food, typically using CO2 as a carbon source
A bacterium that cannot survive on minimal medium (glucose alone) because it lacks the ability to synthesize a molecule it needs to live (typically an amino acid)
must have the needed substance (the auxillary trophic substance) added to their medium in order to survive.
typically denoted by the substance they require followed by a"-" sign in superscript.
For example, a bacterium that cannot synthesize leucine would be a leucine auxotroph and would be indicated as Leu-.
Lacking a blood supply,
A long projection off the cell body of a neuron down which an action potential can be propagated.
type of lymphocyte that can recognize (bind to) an antigen and secrete an antibody specific for that antigen.
when activated by binding an antigen, B cells mature into plasma cells (that secrete antibody) and memory cells (that patrol the body for future encounters with that antigen)
A bacterium having a rod-like shape (plural = bacilli).
A virus that infects a bacterium.
A sensory receptor that responds to changes in pressure
for example, there are baroreceptors in the carotid arteries and the aortic arch that monitor blood pressure.
see "vestibular glands."
A layer of collagen fibers that separates epithelial tissue from connective tissue.
The flexible membrane in the cochlea that supports the organ of Corti (the structure that contains the hearing receptors).
The fibers of the basilar membrane are short and stiff near the oval window and long and flexible near the apex of the cochlea.
This difference in structure allows the basilar membrane to help transduce pitch.
This ion results from dissociation of carbonic acid
together with carbonic acid, form the major blood buffer system.
also secreted by the pancreas to neutralize stomach acid in the intestines.
see "atrioventicular valve"
A green fluid made from cholesterol and secreted by the liver.
stored and concentrated in the gallbladder.
an amphipathic molecule that is secreted into the small intestine when fats are present, and serves to emulsify the fats for better digestion by lipases.
An asexual method of bacterial reproduction that serves only to increase the size of the population
there is no introduction of genetic diversity.
The bacterium simply grows in size until it has doubled its cellular components, then it replicates its genome and splits into two.
A neuron with a single axon and a single dendrite. often projecting from opposite sides of the cell body.
typically associated with sensory organs
example = the bipolar neurons in the retina of the eye.
A cell in the retina of the eye that receives input from photoreceptors and subsequently synapses on ganglion cells.
apart of bipolar neurons
A fluid-filled sphere formed about 5 days after fertilization of an ovum
made up of an outer ring of cells and an inner cell mass.
This is the structure that implants in the endometrium of the uterus.
The tendency of certain factors to stabilize hemoglobin in the tense conformation, thus reducing its affinity for oxygen and enhancing the release of oxygen to the tissues.
The factors include:
•increased bisphosphoglycerate (BPG)
Note that the Bohr effect shifts the oxy-hemoglobin saturation curve to the right.
boiling point elevation
The increase in the boiling point of a solution due to the addition of solute.
A non-bony material that fills the hollow spaces inside bones.
Red bone marrow is found in regions of spongy bone and is the site of blood cell production.
Yellow bone marrow is found in the diaphysis (shaft) of long bones, is mostly fat, and is inactive.
bottom -up processing
A tenet of Gestalt psychology wherein the processing of sensory input begins with the sensory receptors and works up to the complex integration of information occurring in the brain.
The region of the nephron that surrounds the glomerulus.
collects the plasma that is filtered from the capillaries in the glomerulus
Very small air tubes in the respiratory system (diameter 0.5-1.0 m.m).
The walls of the bronchioles are made of smooth muscle to help regulate air flow.
brush border enzymes
Enzymes secreted by the mucosal cells lining the intestine.
disaccharidases and dipeptidases that digest the smallest carbohydrates and peptides in to their respective monomers.
small, paired glands found inferior to the prostate in males and at the posterior end of the penile urethra.
They secrete an alkaline mucus on sexual arousal that lubricate the urethra and helps to neutralize any traces of acidic urine in the urethra that might be harmful to sperm.
Bundle of His
See "atriventricular (AV) bundle."
A hormone produced by the C-cells of the thyroid gland that decreases serum calcium levels.
It targets the bones (stimulates osteoblasts) and the kidneys (reduces calcium re-absorption.
8.6 and 11.9
A hormone produced from Vitamin D that acts to increase serum calcium levels.
A cytoplasmic Ca2+ binding protein.
particularly important in smooth muscle cells, where binding of Ca2+ allows calmodulin to activate myosin light-chain kinase, the first step in smooth muscle cell contraction.
An increase in the fragility of the membranes of sperm cells when exposed to the female reproductive tract.
required so that the acrosomal enzymes can be released to facilitate fertilization.
The smallest of all blood vessels, typically having a diameter just large enough for blood cells to pass through in single file.
extremely thin walls to facilitate the exchange of material between the blood and the tissues.
The outer protein coat of a virus.
An enzyme present in erythrocytes (as well as in other places) that catalyzes the conversion of CO2 and H20 into carbonic acid.
cardiac conduction system
The specialized cells of the heart that spontaneously initiate action potential and transmit them to the cardiac muscle cells.
The cells of the conduction system are essentially cardiac muscle cells, but lack the contractile fibers of the muscle cells,
thus they are able to transmit impulses (action potentials) more quickly and efficiently than cardiac muscle tissue. The cardiac conduction system includes:
•the SA node
•the internodal tract
•the AV node
•the AV bundle
•the right and left bundle
•the Purkinje fibers.
The muscle tissue of the heart.
striated, uninucleate, and under involuntary control (controlled by the autonomic nervous system).
Note also that cardiac muscle is self-stimulatory and autonomic control serves only to modify the intrinsic rate of contraction.
The volume of blood pumped out of the heart in one minute (vol/min);
the product of the stroke volume (vol/beat) and the heart rate (beat/min).
directly proportional to blood pressure.
see "lower esophageal sphincter."
An integral membrane protein that undergoes a conformational change to move a molecule from one side of the membrane to another.
See also "uniporter", "antiporter", and symporter"
A strong connective tissue with varying degrees of flexibility.
Elastic cartilage is the most flexible, forming structures that require support but also need to bend, such as the epiglottis and outer ear.
Hyaline cartilage is more rigid than elastic cartilage and forms the cartilage of the ribs, the respiratory tract and all joints.
Fibrocartilage is the least flexible of them all, and forms very strong connections, such as the pubic symphysis and the intervertebral disks.
A family of proteases that carry out the events of apoptosis.
Something that increases the rate of a chemical reaction by reducing the activation energy for the reaction. The G of the reaction remains unchanged.
DNA produced synthetically by reverse transcribing mRNA.
Because of eukaryotic mRNA splicing, cDNA contains no introns.
The first part of the large intestine.
cell surface receptor
An integral membrane protein that binds extracellular signaling molecules such as hormones and peptides.
Established by Robert Hooke in 1655
asserts that all living organism are composed of one or more cells
and that new cells arise from preexisting, living cells.
AKA Haversian canal
The hollow center of an osteon
contains blood vessels, lymphatic vessels and nerves.
Bone is laid down around the central canal in concentric rings called Lamellae.
Receptors in the central nervous system that monitor the pH of cerebrospinal fluid to help regulate ventilation rate.
central nervous system
The subdivision of the nervous system consisting of the brain and spinal cord.
A structure composed of a ring of nine microtubule triplets,
found in pairs at the MTOC (microtubule organizing center) of a cell.
duplicate during cell division and serve as the organizing center for the mitotic spindle
A structure near the middle of eukaryotic chromosomes to which the fibers of the mitotic spindle attach during cell division.
The region of the brain that coordinates and smoothes skeletal muscle activity.
A thin (4mm) layer of gray matter on the surface of the cerebral hemispheres.
the conscious mind,
functionally divided into four pairs of lobes:
•the frontal lobes
•the parietal lobes
•the temporal lobes
•the occipital lobes
cerebrospinal fluid (CSF)
A clear fluid that circulates around and through the brain and spinal cord.
helps to physically support the brain and acts as a shock absorber.
also exchanges nutrients and wastes with the brain and spinal cord.
The opening of the uterus.
typically plugged with a sticky acidic mucus during non-fertile times (to form a barrier against the entry of pathogens)
however during ovulation the mucus becomes more watery and alkaline to facilitate sperm entry.
An integral membrane protein that selectively allows molecules across the plasma membrane.
See also entries under "ion channel," "voltage-gated channel," and ligand-gated channel."
A family of proteins that assists in the folding of other proteins
A type of synapse at which a chemical (a neurotransmitter) is released from the axon of a neuron into the synaptic cleft where it binds to receptors on the next structure in sequence, either another neuron or an organ.
A sensory receptor that responds to specific chemicals.
Some examples are: •gustatory (taste) receptors
•olfactory (smell) receptors
•central chemoreceptors (respond to pH change in the cerebrospinal fluid).
5.3 and 8.5
Movement that is directed by chemical gradients such as nutrients or toxins.
5.3 and 9.4
An organism that relies on a chemical source of energy (such as ATP) instead of using light to make ATP (like phototrophs do)
Pepsinogen-secreting cells found at the bottom of the gastric glands of the stomach.
A polysaccharide found in the cell walls of fungi and in the exoskeletons of insects.
A hormone secreted by the small intestine (duodenum) in response to the presences of fats.
promotes release of bile from the gallbladder and pancreatic juice from the pancreas
reduces stomach motility.
A large, ring-shaped lipid found in cell membranes.
precursor for steroid hormones
used to manufacture bile salts.
3.4 and 6,3
A mature cartilage cell.
The portion of the placenta derived from the zygote.
The chorionic villi secrete hCG to help maintain the endometrium during the first trimester of a pregnancy.
The darkly pigmented middle layer of the eyeball, found between the sclera (outer layer) and the retina (inner layer).
A single piece of double -stranded DNA;
part of the genome of an organism.
Prokaryotes have circular chromosomes
Eukaryotes have linear chromosomes.
A type of lipoprotein;
the form in which absorbed fats from the intestines are transported to the circulatory system.
9.5 and 10.7
Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach.
One of the main pancreatic proteases;
it is activated ( from chymotrypsinogen) by trypsin.
A hair-like structure on the cell surface composed of microtubules in a "9 + 2" arrangement (nine pairs of microtubules surrounding 2 single microtubules in the center).
The microtubules are connected with a contractile protein called dynein.
Cilia beat in a repetitive sweeping motion, which helps to move substances along the surface of the cell.
particularly important in the respiratory system, where they sweep mucus out of the trachea and up to the mouth and nose.
circular smooth muscle
The inner layer of smooth muscle in the wall of the digestive tract.
When the circular muscle contracts, the tube diameter is reduced.
Certain areas of the circular muscle are thickened to act as valves (sphincters).
A fibrous protein found on the intracellular side of the plasma membrane (also found associated with the Golgi complex) that helps to invaginate the membrane.
Typically cell surface receptors are associated with clathrin-coated pits at the plasma membrane, and binding of the ligand to the receptor triggers invagination.
The rapid mitotic divisions of a zygote that begin within 24-36 hours after fertilization.
A bacterium having a round shape (plural = cocci)
The curled structure in the inner ear that contains the membranes and hair cells used to transduce sound waves into action potentials.
A situation in which a heterozygote displays the phenotype associated with each of the alleles,
e.g., human blood type AB.
A group of three nucleotides that is specific for a particular amino acid or that specifies "stop translating."
A protein fiber with a unique triple-helix structure that gives it great strength.
Tissues with a lot of collagen fibers are typically very strong, e.g, bone, tendons, ligaments, etc.
The portion of the nephron where water reabsorption is regulated via antidiuretic hormone (ADH).
Several nephrons empty into each collecting duct, and this is the final region through which urine must pass on its way to the ureter.
Properties that depend on the number of solute particles in a solution rather than on the type of particle.
•boiling point elevation
•freezing point depression •vapor pressure depression
See "Large intestine."
10.1 and 10.6
common bile duct
The duct that carries bile from the gallbladder and liver to the small intestine (duodenum)
A dense, hard type of bone constructed from osteons (at the microscopic level).
forms the diaphysis of the long bones, and the outer shell of the epiphyses and all other bones.
A group of blood protein that bind non-specifically to the surface proteins of foreign cells (such as bacteria), ultimately leading to the destruction of the foreign cell.
Photoreceptores in the retina of the eye that respond to bright light and provide color vision.
A form of generic recombination in bacteria in which plasmid and /or genomic DNA is transferred from one bacterium to the other through a conjugation bridge.
One of the four basic tissue types in the body (epithelial, connective, muscle, and nervous).
a supportive tissue consisting of relatively few cells scattered among a great deal of extracellular material (matrix), and includes:
•adipose tissue (fat)
•the dermis of the skin
A form of evolution in which different organisms are placed into the same environment and exposed to the same selection pressures.
This causes the organisms to evolve along similar lines.
As a result, they may share functional, but not structural similarity (because they possessed different starting material).
produces analogous structures.
A type of substrate binding to a multi-active site enzyme, where binding of one substrate modulates the binding of subsequent substrate molecules
positive if the substrate affinity of the other subunits increases
negative if the substrate affinity of the other subunits decreases
Sigmoidal graph of reaction rate vs. substrate concentration
can be found in other situations: hemoglobin binds oxygen with positive cooperativity (not sure about the positive, check again)
copy number variation
structural variation in the genome that lead to different copies of certain sections of the DNA, due to duplication of those sections or deletions of those sections.
The clear portion of the tough outer layer of the eyeball, found over the iris and pupil.
The layer of granulosa cells that surround an oocyte after it has been ovulated.
The blood vessels that carry blood to and from cardiac muscle.
The coronary arteries branch off the aorta and carry oxygenated blood to the cardiac tissue.
The coronary veins collect de-oxygenated blood from the cardiac tissue, merge to form the coronary sinus, and drain into the right atrium.
The largest bundle of white matter (axons) connecting the two cerebral hemispheres.
The remnants of an ovarian follicle after ovulation has occured.
The cells enlarge and begin secreting progesterone, the dominant female hormone during the second half of the menstrual cycle.
Some estrogen is also secreted.
The outer layer of an organ,
e.g, the renal cortex, the ovarian cortex, the adrenal cortex, etc.
8.4, 8.5, 8.6, and 10.2
see "slow block to polyspermy."
Steroid hormones secreted from the adrenal cortex.
The two major classes are the mineralocorticoids and glucocorticoids.
Aldosterone is the principal mineralocorticoid
cortisol is the principal glucocorticoid.
The principal glucocorticoid secreted from the adrenal cortex.
released during stress, causing increased blood glucose levels and reducing inflammation.
The latter effect has led to a clinical use of cortisol as an anti-inflammatory agent.
An energy storage molecule used by muscle tissue.
The phosphate from creatine phosphate can be removed and attached to an ADP to generate ATP quickly.
The connection of a myosin head group to an actin filament during muscle contraction (the sliding filament theory).
The exchange of DNA between paired homologous chromosomes (tetrads) during prophase 1 of meiosis.
cyclic AMP (cAMP)
AKA second messenger
cyclic version of adenosine monophosphate, where the phosphate is esterified to both the 5' and the 3' carbons, forming a ring.
important intracellular signaling molecule
serves to activate cAMP-dependent kinases, which regulate the activity of other enzymes in the cell.
Levels of cAMP are in part regulated by adenylyl cyclase, the enzyme that makes cAMP
the activity of adenylyl cyclase is ultimately controlled by the binding of various ligands to cell surface receptors.
The phase of mitosis during which the cell physically splits into two daughter cells.
begins near the end of anaphase, and is completed during telophase.
1 of 4 aromatic bases found in DNA and RNA.
pyrimidine and it pairs with guanine.
A projection off the cell body of a neuron that receives a nerve impulse from a different neuron and sends the impulse to the cell body.
Neurons can have one or several dendrites.
dense connective tissue
connective tissue with large amounts of either collagen fibers or elastic fibers, or both.
Dense tissues are typically strong (e.g., bone, cartilage, tendons, etc.)
The movement of the membrane potential of a cell away from rest potential in a more positive direction.
A layer of connective tissue underneath the epidermis of the skin.
A general cell junction used primarily for adhesion.
The point during cellular development at which a cell becomes committed to a particular fate.
Note that the cell is not differentiated at this point;
comes before differentiation.
can be due to cytoplasmic effects or to induction by neighboring cells.
The primary muscle of inspiration.
stimulated to contract at regular intervals by the respiratory center in the medulla oblongata (via the phrenic nerve).
Although it is made of skeletal muscle (and can therefore be voluntarily controlled), these stimulations occur autonomously.
The shaft of a long bone.
hollow and is made entirely from compact bone.
The period of time during which the ventricles of the heart are relaxed.
The pressure measured in the arteries while the ventricles are relaxed (during diastole)
The portion of the forebrain that includes the thalamus and hypothalamus.
The minimum noticeable difference between any two sensory stimuli, 50% of the time.
The specialization of cell types, especially during embryonic and fatal development.
The movement of a particle (the solute) from its region of high concentration to its region of low concentration (or down its concentration gradient)
An organism that has two copies of its genome in each cell. The paired genomes are said to be homologous.
distal convoluted tubule
The portion of the nephron tubule after the loop of Henle, but before the collecting duct.
Selective reabsorption and secretion occur here;
most notably regulated reabsorption of water and sodium.
A form of evolution in which the same organism is placed into different environments with different selection pressures.
This causes the organisms to evolve differently; to diverge from their common ancestor.
The resulting (new) species may share structural (but not necessarily functional) similarity;
produces homologous structures.
AKA DNA pol
enzyme that replicates DNA.
Eukaryotes have a single version of the enzyme, simply called DNA pol;
Prokaryotes have three versions, called
DNA pol 1, 2, and 3.
One of the three main taxonomic domains
live in the world's most extreme environments (hot springs, hypersaline environments etc.)
They possess characteristics of both prokaryotes and eukaryotes.
1. The allele in a heterozygous genotype that is expressed.
2. The phenotype resulting from either a heterozygous genotype or a homozygous dominant genotype.
dorsal root ganglion
A group of sensory neuron cell bodies found just posterior to the spinal cord on either side. (behind the spinal cord)
A pair of root ganglia exists for each spinal nerve that extends from the spinal cord.
The ganglia are part of the peripheral nervous system (PNS).
Towards the 3' end of an RNA transcripts (the 3' end of the DNA coding strand).
Stop codons and (in eukaryotes) the poly -A tail are found "downstream."
A thick muscular tube that connects the epididymis of the testes to the urethra.
Muscular contractions of the vas deferens during ejaculation helps propel the sperm onward. Severing of the vas deferens (vasectomy) results in sterility of the male.
The first part (approximately 5 percent) of the small intestine.
A contractile protein connecting microtubules in the "9 + 2 arrangement of cilia and eukaryotic flagella.
The contraction of dynein produces the characteristic movements of these structures.
One of the three primary (embryonic) germ layers formed during gastrulation.
ultimately forms external structures:
•inner linings of the mouth and anus
•entire nervous system.
The small artery that carries blood away from the capillaries of the glomerulus.
A neuron that carries information (action potentials) away from the central nervous system
a motor neuron
A subphase of male orgasm, a reflex reaction triggered by the presence of semen in the urethra.
a series of rhythmic contractions of muscles near the base of the penis that increase pressure in the urethra, forcing the semen out.
The fraction of the end-diastolic volume ejected from the ventricles in a single contraction of the heart.
normally around 60 percent of the end-diastolic volume.
A fibrous, connective-tissue protein that has the ability to recoil to its original shape after being stretched.
found in great amounts in:
A type of synapse in which the cells are connected by gap junctions, allowing ions (and therefore an action potential) to spread easily from cell to cell.
electron transport chain (ETC)
A series of enzyme complexes found along the inner mitochondrial membrane.
NADH and FADH2 are oxidized by these enzymes
the electrons are shuttled down the chain and are ultimately passed to oxygen to produce water.
The electron energy is used to pump H+ out of the mitochondrial matrix; the resulting H+ gradient is subsequently used to drive the production of ATP.
2.5, 5.1, 6.2
Proteins that assist with peptide bond formation during eukaryotic translation.
The period of human development from implantation through eight weeks of gestation.
Gastrulation, neurulation and organogenesis occur during this time period. T
he developing baby is known as a embryo during this time period.
A subphase of male orgasm.
movement of sperm (via the ductus deferens) and semen (via the accessory glands) into the urethra in preparation for ejaculation.
A ductless gland that secretes a hormone into the blood.
A system of ductless glands that secrete chemical messengers (hormones) into the blood.
The uptake of material into a cell, usually by invagination.
See also "phagocytosis," "pinocytosis," and receptor-mediated endocytosis."
5.1 and 6.4
One of the three primary (embryonic) germ layers formed during gastrulation.
ultimately forms internal structures, such as the inner lining of the GI tract and some glandular organs.
AKA uterine cycle
The 28 days of the menstrual cycle as they apply to the events in the uterus.
has three subphases:
•the proliferative phase
•the secretory phase
The inner epithelial lining of the uterus that thickens and develops during the menstrual cycle, into which a fertilized ovum can implant, and which sloughs off during menstruation if a pregnancy does not occur.
A bacterial structure formed in unfavorable growth conditions.
have very tough outer shells made of peptidoglycan and can survive harsh conditions.
The bacterium inside the endospore is essentially dormant and can become active (called germination) when conditions again become favorable.
The theory that mitochondria and chloroplasts originated as independent unicellular organisms living in symbiosis with larger cells.
A normal component of the outer membrane of Gram-negative bacteria.
produce extreme immune reaction (septic shock), particularly when many of them enter the circulation at once.
end plate potential
The depolarization of the motor end plate on a muscle cell.
enteric nervous system
The nervous system of the gastrointestinal tract.
It controls secretion and motility within the GI tract, and is linked to the central nervous system.
A hormone secreted by the small intestine (duodenum) in response to the presence of food.
It decreases the rate at which chyme leaves the stomach and enters the small intestine.
A duodenal enzyme that activates trypsinogen (from the pancreas) to trypsin.
A lipid bilayer that surrounds the capsid of an animal virus.
The envelope is acquired as the virus buds out through the plasma membrane of its host cell.
Not all animal viruses possess an envelope.
The outermost layer of the skin.
made of epithelial tissue that is constantly dividing at the bottom;
the cells migrate to the surface (dying along the way) to be sloughed off at the surface.
A long coiled duct on the outside of the testis in which sperm mature.
Changes in gene expression that are not due to mutations, but are long-term and heritable
(e.g., DNA methylation, chromatin remodeling, and RNA interference).
A flexible piece of cartilage in the larynx that flips downward to seal the trachea during swallowing.
10.6 and 12.2
A hormone produced and secreted by the adrenal medulla that prolongs and increases the effects of the sympathetic nervous system.
A band of cartilage (hyaline) found between the diaphysis and epiphyses of long bones during childhood and adolescence.
Cell proliferation in the middle of the epiphyses plate essentially forces the diaphysis and epiphyses further apart while the older cartilage at the edges of the plate is replaced with bone.
This is what allows bone growth during childhood.
gets thinner and thinner the older a person gets until finally it fuses (the diaphysis and epiphyses connect) in late adolescence, preventing further elongation of the bones.
One of the two ends of a long bone (pl: epiphyses).
epiphyses have an outer shell made of compact bone and an inner core of spongy bone.
The spongy bone is filled with red bone marrow, the site of the blood cell formation.
A situation in which the expression of one gene prevents expression of all allelic forms of another gene
e.g., the gene for male pattern baldness is epistatic to the hair color gene.
One of the four basic tissue types in the body (epithelial, connective, muscle, and nervous)
lining and covering tissue e.g.
•the lining of the stomach and intestines
•the lining of the urinary tract, etc.)
or a glandular tissue (e.g. the liver, the pancreas, the ovaries, etc.)
The specific site on an antigenic molecule that binds to a T-cell receptor or to an antibody.
The membrane potential at which there is no driving force on an ion, and there is no net movement of ions across the membrane.
AKA Excitatory postsynaptic potential
a slight depolarization of a postsynaptic cell, bringing the membrane potential of that cell closer to the threshold for an action potential.
Specialized tissue with a lot of space that can fill with blood upon proper stimulation, causing the tissue to become firm.
found in the penis, the clitoris, the labia and the nipples.
A red blood cell;
filled with hemoglobin
function of the erythrocytes is to carry oxygen in the blood.
A hormone produced and released by the kidney that stimulates the production of red blood cells by the bone marrow.
The primary female sex hormone.
•stimulates the development of female secondary sex characteristics during puberty
•maintains those characteristics during adulthood
•stimulates the development of a new uterine lining after menstruation
•stimulates mammary gland development during pregnancy.
A cell characterized by the presence of a nucleus and other membrane-bound organelles.
Eukaryotes can be unicellular (protists) or multicellular (fungi, plants and animals).
The removal (and usually the activation) of a viral genome from its host's genome.
The mechanism that ensures that skeletal muscle contraction does not occur without neural stimulation (excitation).
At rest, cytosolic [Ca2+] is low, and the troponin-tropomyosin complex covers the myosin-binding sites on actin.
When the muscle is stimulated by neuron, Ca2+ is released from the sarcoplasmic reticulum into the cytosol of the muscle cell.
Ca2+ binds to troponin, causing a conformation change in the troponin- tropomyosin complex that shifts it away from the myosin-binding sites.
This allows myosin and actin to interact according to the sliding filament theory.
The elimination of waste products from the body.
A gland that secretes its product into a duct, which ultimately carries the product to the surface of the body cavity.
Some examples of exocrine glands and their products are:
•sweat glands (sweat)
•gastric glands (acid, mucus, protease)
•the liver (bile)
•sebaceous glands (oil)
•lacrimal glands (tears).
The secretion of a cellular product to the extracellular medium through a secretory vesicle.
A nucleotide sequence in RNA that contains protein-coding information.
typically separated by introns (intervening sequence) that are spliced out prior to translation.
A toxin secreted by a bacterium into its surrounding medium that help the bacterium compete with other species.
Some exotoxins cause serious diseases in humans (botulism, tetanus, diphtheria, toxic shock syndrome).
The movement of air out of the respiratory tract.
can be passive (caused by relaxation of the diaphragm and elastic recoil of the lungs)
or active (caused by contraction of the abdominal muscles, which increases intra-abdominal pressure and forces the diaphragm up past its normal relaxed position).
Movement of a hydrophilic molecule across the plasma membrane of a cell, down its concentration gradient, through a channel, pore, or carrier molecule in the membrane.
Because of the hydrophilic nature of the molecule, it requires a special path through the lipid bilayer.
An organism that will use oxygen to produce energy (aerobic metabolism) if it is available, and that can ferment (anaerobic metabolism) if it is not.
See "Uterine tubes."
A bundle of skeletal muscle cells.
group together to form skeletal muscles.
fast block to polyspermy
The depolarization of the egg plasma membrane upon fertilization, designed to prevent the entry of more than one sperm into the egg.
The fusion of a sperm with an ovum during sexual reproduction.
In humans, fertilization typically occurs in the uterine tubes and requires capacitation of the sperm and release of the acrosomal enzymes.
a species-specific process, requiring binding of a sperm protein to an egg receptor.
F (fertility) factor
A bacterial plasmid that allows the bacterium to initiate conjugation.
Bacteria that posses the F factor are known as F+ "males."
The period of human development beginning at eight weeks of gestation and lasting until birth (38-42 weeks of gestation).
During this stage the organs formed in the embryonic stage grow and mature.
The developing baby is known as a fetus during this time period.
A blood protein essential to blood clotting.
The conversion of fibrinogen to its active form (fibrin) is among the final steps in clot formation, and is triggered by thrombin
A generic connective tissue cell that produces fibers;
the progenitor of all other connective tissue cell types.
The movement of a substance across a membrane via pressure.
In the kidney, filtration refers specifically to the movement of plasma across the capillary walls of the glomerulus, into the capsule and tubule of the nephron.
Filtration at the glomerulus is driven by blood pressure.
Fingerlike projections of the uterine (fallopian) tubes that drape over the ovary.
A long, whip-like filament that helps in cell motility.
Many bacteria are flagellated, and sperm are flagellated.
fluid mosaic model
The current understanding of membrane structure, in which the membrane is composed of a mix of lipids and proteins (a mosaic) that are free to move fluidly among themselves.
A developing oocyte and all of its surrounding (supporting) cells.
follicle stimulating hormone (FSH)
A tropic hormone produced by the anterior pituitary gland that targets the gonads.
In females, FSH stimulates the ovaries to develop follicles (oogenesis) and secrete estrogen;
in male, FSH stimulates spermatogenesis.
The first phase of the ovarian cycle during which a follicle (an oocyte and its surrounding cells) enlarges and matures.
The phase is under the control of FSH from the anterior pituitary and typically lasts from day 1 to day 14 of the menstrual cycle.
The follicle secretes estrogen during this time period.
The first generation of offspring from a given genetic cross.
The cellular elements of blood; erythrocytes, leukocytes and platelets.
A modified methionine used as the first amino acid in all prokaryotic protein.
A mutation caused by an insertion or deletion of base pairs in a gene sequence in DNA such that the reading frame of the gene (and thus the amino acid sequence of the protein) is altered.
the stroke volume of the heart is increased by increasing the venous return to the heart (thus stretching the ventricular muscle).
The decrease in the freezing point of a solution due to the addition of solute.
A tissue in which the cytoplasms of the cells are connected by gap junctions, allowing the cells to function as a unit.
Cardiac and smooth muscle tissue are examples of functional synctiums.
A digestive accessory organ near the liver.
The gall bladder stores and concentrates bile produced by the liver, and is stimulated to contract by cholecystokinin (CCK)
The formation of haploid gametes (sperm or ova) via meiosis.
A clump of gray matter (un-myelinated neuron cell bodies) found in the peripheral nervous system.
A junction formed between cells, consisting of a protein channel called a connexon on each of the two cells, that connect to form a single channel between the cytoplasms of both cells.
allow small molecules to flow between the cells and are important in cell-to- cell communication
for example, in relaying the action potential between cardiac muscle cells, and relaying nutrients between osteocytes.
6.5 and 9.2
A phase in the cycle between mitosis and S phase (G1) or between S phase and mitosis (G2).
During gap phases the cell undergoes normal activity and growth;
G1 may include preparation for DNA replication
G2 includes preparation for mitosis.
Note that non-dividing cells remain permanently in G1, known as Go for these cells.
A hormone released by the G cells of the stomach in the presence of food.
promotes muscular activity of the stomach as well as secretion of hydrochloric acid, pepsinogen and mucus.
The division of the inner cell mass of a blastocyst (developing embryo) into the three primary germ layers.
Gastrulation occurs during weeks 2-4 of gestation.
A portion of DNA that codes for some product, usually a protein, including all regulatory sequences.
Some genes code for rRNA and tRNA, which are not translated.
4.3 and 7.1
The sum of all genetic information in a population.
The "language" of molecular biology that specifies which amino acid corresponds to which three nucleotide group (a codon).
All the genetic information is an organism;
all of an organism's chromosomes.
The combination of alleles an organism carries.
In a homozygous genotype, both alleles are the same
in a heterozygous genotype the alleles are different.
Specialized non-neuronal cells that provide structural and metabolic support to neurons
for example, the Schwann cell.
The ball of capillaries at the beginning of the nephron where blood filtration takes place.
A peptide hormone produced and secreted by the or cells of the pancreas.
It targets primarily the liver, stimulating the breakdown of glycogen, thus increasing blood glucose levels.
Inhibitory neurotransmitter released onto bipolar cells in the retina by rods and cones.
The release of glutamate is stopped when light hits the photoreceptor, and the subsequent cessation in glutamate releases the inhibition on the bipolar cell, causing it to fire.
A membrane lipid consisting of a glycerol molecule esterified to two fatty acid chains and sugar molecule.
Unicellular exocrine glands found along the respiratory and digestive tracts that secrete mucus.
A stack of membranes found near the rough ER in eukaryotic cells that is involved in the secretory pathway.
involved in protein glycosylation (and other protein modification) as well as sorting and packaging proteins.
gonadotropin releasing hormone (GnRH)
A hormone released from the hypothalamus that triggers the anterior pituitary to secrete FSH and LH.
Anterior pituitary tropic hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) that stimulate the gonads (tests and ovaries) to produce gametes and to secrete sex steroids.
(Basically that gonadotropins = FSH and LH)
G-protein linked receptor
A cell surface receptor associated with an intracellular protein that binds and hydrolyzes GTP.
When GTP is bound, the protein is active, and can regulate the activity of adenylyl cyclase;
this modifies the intracellular levels of the second messenger cAMP.
When the GTP is hydrolyzed to GDP, the protein becomes inactive again.
A large, mature, ovarian follicle with a well-developed antrum and secondary oocyte.
Ovulation of the oocyte occurs from this type of follicle.
Bacteria that have a thin peptidoglycan cell wall covered by an outer plasma membrane.
They stain very lightly (pink) in Gram stain.
typically more resistant to antibiotics than Gram-positive bacteria.
Bacteria that have a thick peptidoglycan cell wall, and no outer membrane.
They stain very darkly (purple) in Gram stain.
The majority of the cells surrounding an oocyte in a follicle.
secrete estrogen during the follicular phase of the ovarian cycle.
Un-myelinated neuron cell bodies and short un-myelinated axons.
growth hormone (GH)
A hormone released by the anterior pituitary that targets all cells in the body.
stimulates whole body growth in children and adolescents and increases cell turnover rate in adults.
1 of 4 aromatic bases found in DNA and RNA.
purine, and pairs with cytosine.
chemoreceptors on the the tongue that respond to chemicals in food.
gyrase (DNA gyrase)
A prokaryotic enzyme used to twist the single circular chromosome of prokaryotes upon itself to form supercoils.
Supercoiling helps to compact prokaryotic DNA and make it sturdier.
Sensory receptors found in the inner ear.
Cochlear hair cells respond to vibrations in the cochlea caused by sound waves
vestibular hair cells respond to changes in position and acceleration (used for balance)
An organism that has only a single copy of its genome in each of its cells.
posses no homologous chromosomes.
A law of population genetics that states that the frequencies of alleles in a given gene pool do not change over time.
There are five assumptions required for this law to hold true:
•no natural selection
•random mating between individuals in the population
•population must be large.
A population meeting all of these conditions, in which the allele frequency is not changing, is said to be in Hardy-Weinberg equilibrium.
AKA Human chorionic gonadotropin
a hormone secreted by the trophoblast cells of a blastocyst (i.e., a developing embryo) that prolongs the life of the corpus luteum, and thus increases the duration and amount of secreted progesterone.
This helps to maintain the uterine lining so that menstruation does not occur.
The presence of the hCG in the blood or urine of a woman is used as a positive indicator of pregnancy.
An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.
The percentage of whole blood made up of erythrocytes.
The typical hematocrit value is between 40-45%.
The synthesis of blood cells (occurs in the red bone marrow)
A gene appearing in a single copy in diploid organisms
e.g..,X-linked genes in human males.
A four-subunit protein found in red blood cells that binds oxygen.
Each subunit contains:
•large multi-ring molecule with an iron atom at its center
one hemoglobin molecule can bind four oxygen molecules in a cooperative manner.
A group of X-linked recessive disorders in which blood fails to clot properly, leading to excessive bleeding if injured.
The stoppage of bleeding
the amount of gas that will dissolve into liquid is dependent on the partial pressure of that gas as well as the solubility of that gas in the liquid.
hepatic portal vein
A vein connecting the capillary bed of the intestines with the capillary bed of the liver.
This allows amino acids and glucose absorbed from the intestines to be delivered first to the liver for processing before being transported throughout the circulatory system.
Experiments with phage and bacteria that definitively determined DNA to be the genetic information of the cell.
Densely packed tightly coiled DNA
generally inactive (i.e., not being transcribed).
An organism that cannot make its own food, and thus must ingest other organisms.
A genotype in which two different alleles are possessed for a given gene.
High frequency of recombination bacterium.
An F+ bacterium that has the fertility factor integrated into its chromosome.
When conjugation takes place, it is able to transfer not only the F factor, but also its genomic DNA.
Heterogeneous nuclear RNA;
the primary transcript made in (only) eukaryotes before splicing. (because prokaryotes don't undergo splicing)
The maintenance of relatively constant internal conditions (such as temperature, pressure, ion balance, pH, etc) regardless of external conditions.
8.6 and 10.1
A pair of similar chromosomes that have the same genes in the same order, but may have different versions (alleles) of those genes.
One of the pair of chromosomes came from Mom in an ovum, and the other came from Dad in a sperm.
Humans have 23 pairs of homologous chromosomes.
Physical structures in two different organism that have structural similarity due to a common ancestor, but may have different functions.
Homologous structures arise from divergent evolution.
A genotype in which two identical alleles are possessed for a given gene.
The alleles can both be dominant (homozygous dominant) or both be recessive (homozygous recessive)
Specific defense of the body by antibodies, secreted into the blood by B cells.
Hard crystals consisting of calcium and phosphate that form the bone matrix
The movement of the membrane potential of a cell away from rest potential in a more negative direction.
AKA subcutaneous layer
layer of fat located under the dermis of the skin.
helps to insulate the body and protects underlying muscles and other structures.
The pituitary gland.
hypothalamic-pituitary portal system
A set of veins that connect to capillary bed in the hypothalamus (the primary capillary plexus) with a capillary bed in the anterior pituitary gland (the secondary capillary plexus).
Releasing and inhibiting factors from the hypothalamus travel along the veins to directly affect cells in the anterior pituitary.
The portion of the diencephalon involved in maintaining body homeostasis.
also controls the release of hormones from the pituitary gland.
The region at the center of an A band of a sarcomere that is made up of myosin only.
gets shorter (and may disappear) during muscle contraction.
The region of a sarcomere made up only of thin filaments.
bisected by a Z line.
I bands alternate with A bands to give skeletal and cardiac muscle a striated appearance.
get shorter (and may disappear completely) during muscle contraction.
The sphincter that separates the final part of the small intestine (the ileum) from the first part of the large intestine (the cecum).
typically kept contracted (closed) so that chyme can remain in the small intestine as long as possible.
stimulated to relax by the presence of food in the stomach.
The final (approximately 55% of the small intestine.
The burrowing of a blastocyst (a developing embryo) into the endometrium of the uterus
typically occurring about a week after fertilization.
Physical change to a gene on DNA, such as methylation or histone binding, that renders it inactive, so that ONLY ONE allele of the gene is expressed.
A situation in which a heterozygote display a blended version of the phenotype associated with each allele
e.g., pure-breeding white-flowered plants crossed with pure-breeding red-flowered plants produces heterozygous offspring plants with pink flowers.
A system (set of genes) where the expression of those genes is stimulated by an abundance of substrate
(e.g., the lac operon).
An irritation of a tissue caused by infection or injury.
characterized by four cardinal symptoms: •redness (rubor)
A protein hormone secreted by the sustenacular cells of the testes or granulosa cells of the ovaries that acts to inhibit the release of FSH from the anterior pituitary.
Eukaryotic proteins that assemble in a complete to begin translation.
General, nonspecific protection to the body, including:
inner cell mass
The mass of cells in the blastocyst that ultimately give rise to the embryo and other embryonic structures (the amnion, the umbilical vessels, etc.)
The movement of air into the respiratory tract.
active process, requiring contraction of the diaphragm.
A peptide hormone produced and secreted by the B cells of the pancreas.
targets all cells in the body, especially the liver and muscle
allows them to take glucose out of the blood (thus lowering blood glucose levels)
integral membrane protein
A protein embedded in the lipid bilayer of a cell
typically cell surface receptors, channels, or pumps.
The divisions between neighboring cardiac muscle cells.
include gap junctions, which allow the cells to function as a unit.
Muscles located in between the ribs that play a role in ventilation.
A chemical secreted by a T cell (usually the helper Ts) that stimulates activation and proliferation of other immune system cells
Cytoskeletal filaments with a diameter in between that of the microtubule and microfilament.
composed of many different proteins and tend to play structural roles in cells.
A neuron found completely within the central nervous system.
typically connect sensory and motor neurons, especially in reflex arcs.
The portion of the cardiac conduction system between the SA node and the AV node.
All of the cell cycle except for mitosis,
Interphase includes G1, S phase, and G2
AKA Leydig cells
cells within the testes that produce and secrete testosterone.
stimulated by luteinizing hormone (LH)
A nucleotide sequence that intervenes between protein-coding sequences.
In DNA, these intervening sequences typically contain regulatory sequences
however in RNA they are simple spliced out to form the mature (translated) transcript.
A protein channel in a cell plasma membrane that is specific for a particular ion, such as Na+ or K+.
constitutively open = leak channels
regulated = voltage-gated or ligand-gated
AKA Inhibitory postsynaptic potential
a slight hyperpolarization of a postsynaptic cell, moving the membrane potential of that cell further from threshold.
A pigmented membrane found just in front of the lens of the eye.
In the center of the iris is the pupil, a hole through which light enters the eyeball.
The iris regulates the diameter of the pupil in response to the brightness of the light.
islets of Langerhans
AKA "islet cells"
the endocrine cells in the pancreas.
Different cell types with the islets secrete:
juxtaglomerular apparatus (JGA)
A contact point between the afferent arteriole of glomerulus and the distal convoluted tubule of the nephron.
It is involved in regulating blood pressure.
cells of the afferent arteriole at the juxtaglomerular apparatus (JGA)
baroreceptors that secrete renin upon sensing a decrease in blood pressure
A protein-based substance secreted by cells of the epidermis as they migrate outward.
makes the cells tougher (better able to withstand abrasion) and helps make skin waterproof.
6.5 and 12.6
Multi-protein complexes that attach the spindle fibers to the centromere of a chromosome.
The folds of the skin that enclose the vaginal and urethral openings in females.
strong contractions of the uterus (stimulated by oxytocin) that force a baby out of the mother's body during childbirth.
part of a positive feedback cycle, during which the baby's head stretches the cervix
that stimulates stretch receptors that activate the hypothalamus
that stimulates the posterior pituitary to release oxytocin
that stimulates strong uterine contractions (labor contractions)
that cause the baby's head to stretch the cervix.
The cycle is broken once the baby is delivered.
A set of genes for the enzymes necessary to import and digest lactose
under the control of a single promotor, whose expression is stimulated by the presence of lactose
(this is an inducible system)
Specialized lymphatic capillaries in the intestines that take up lipids as well as lymph.
9.5 and 10.6
Small cavities in bone or cartilage that hold individual bone or cartilage cells.
The newly forming daughter strand of DNA that is replicated in a discontinuous fashion, via Okazaki fragments that will ultimately be ligated together;
the daughter strand that is replicated in the opposite direction that the parental DNA is unwinding.
A short period of time prior to exponential growth of a bacterial population during which no, or very limited, cell division occurs.
The final part of the digestive tract, also called the colon.
The primary function is to reabsorb water and to store feces.
A rigid structure at the top of the trachea made completely out of cartilage.
has three main functions:
•1) its rigidness ensures that the trachea is held open (provides an open airway).
•2) the epiglottis folds down to seal the trachea during swallowing, thus directing food to the esophagus
•3) this is where the vocal cords are found (voice production).
A dense growth of bacteria that covers the surface of a petri dish.
Law of independent assortment
Mendel's second law.
genes found on different chromosomes, or genes found very far apart on the same chromosome (i.e., unlinked genes) sort independently of one another during gamete formation (meiosis).
Law of Segregation
Mendel's first law
AKA Principal of segregation
two alleles of a given gene will be separated from one another during gamete formation (meiosis).
The newly forming daughter strand of DNA that is replicated in a continuous fashion
the daughter strand that is replicated in the same direction that the parental DNA is unwinding.
An ion channel that is constitutively open, allowing the movement of the ion across the plasma, membrane according to its concentration gradient.
The relationship of muscle length to its ability to generate strong contractions.
Maximum tension (contraction strength) is achieved at sarcomere lengths between 2.0 and 2.2 microns.
Tension decreases outside of this range.
A white blood cell;
involved in disease defense.
see "interstitial cell."
A strong band of connective tissue that connects bones to one another.
The specific molecule that binds to a receptor.
ligand-gated ion channel
An ion channel that is opened or closed based on the binding of a specific ligand to the channel.
Once opened, the channel allows the ion to cross the plasma membrane according to its concentration gradient.
An example is the acetylcholine receptor at the neuro-muscular junction, which when ACh binds, opens a cation channel in the muscle cell membrane.
AKA DNA ligase
An enzyme that connects two fragments of DNA to make a single fragment;
used during DNA replication and is also used in recombinant DNA research.
The failure of two separate genes to obey the Law of Independent Assortment, as might occur if the genes were found close together on the same chromosome.
large conglomerations of protein, fats, and cholesterol that transport lipids in the blood stream
3.4 and 9.4
The largest organ in the abdominal cavity.
has many roles including: •processing of carbohydrates and fats
•synthesis of urea
•production of blood proteins
•production of bile
•recycling of heme
•storage of vitamins
The ability of tissue to regulate their own blood flow in the absence of neural stimulation.
generally accomplished via metabolic wastes (such as CO2) that act as vasodilators.
The period of exponential growth of a bacterial population.
The most common class of bone in the body,
well-defined shaft (the diaphysis)
[and] two well-defined ends (the epiphyses)
The outer layer of smooth muscle in the wall of the digestive tract.
When the longitudinal muscle contracts, the tube shortens.
loop of Henle
The loop of the nephron tubule that dips downward into the renal medulla.
sets up a concentration gradient in the kidney so that osmolarity increases from the cortex to the renal pelvis
The descending limb of the loop of Henle is permeable to water, but not to sodium
The ascending limb is permeable to sodium, but not to water (and actively transports sodium out of the filtrate)
loose connective tissue
Connective tissue that lacks great amount of collagen or elastic fibers
e.g., adipose tissue and areolar (general connective) tissue.
lower esophageal sphincter
Formerly called the cardiac sphincter
marks the entrance to the stomach.
prevent reflux of acidic stomach content into the esophagus
note that it does not regulate entry into the stomach.
The inside of a hollow organ
(e.g., the stomach, intestines, bladder, etc.)
or a tube (e.g., blood vessels, ureters, etc.)
6.2 and 10.5
The third phase of the ovarian cycle, during which a corpus luteum is formed from the remnants of the follicle that has ovulated its oocyte.
The corpus luteum secretes progesterone and estrogen during this time period, which typically lasts from day 15 to day 28 of the menstrual cycle.
Formation of the corpus luteum is triggered by the same LH surge that triggers ovulation, however in the absence of LH (levels quickly decline after the surge), the corpus luteum begins to degenerate.
luteinizing hormone (LH)
A tropic hormone produced by the anterior pituitary gland that targets the gonads.
In females LH triggers ovulation and the development of the corpus luteum during the menstrual cycle
in males, LH stimulates the production and release of testosterone.
A set of vessels in the body that runs alongside the vessels of the circulatory system.
It is a one-way system, with lymphatic capillaries beginning at the tissues and ultimately emptying into the large veins near the heart.
It serves to return excess tissue fluid (lymph) to the circulatory system, and filters that fluid through millions of white blood cells on its way back to the heart.
A concentrated region of white blood cells found along the vessels of the lymphatic system.
The second most common of the five classes of leukocytes.
Lymphocytes are involved in specific, immunity and include two cell types, B cells and T cells.
B cells produce and secrete antibodies
T cells are involved in cellular immunity.
A chemical secreted by a T cell (usually the helper Ts) that stimulates activation and proliferation of other immune system cells.
A viral life cycle in which the viral genome is incorporated into the host genome where it can remain dormant for an unspecified period of time.
Upon activation, the viral genome is excised from the host genome and typically enters the lytic cycle.
A eukaryotic organelle filled with digestive enzymes (acid hydrolases) that is involved in digestion of macromolecules such as worn organelles or material ingested by phagocytosis.
An enzyme that lyses bacteria by creating holes in their cell walls.
produced in the end stages of the lytic cycle so that new viral particles can escape their host
it is also found in human tears and human saliva.
A viral life cycle in which the host is turned into a "virus factory" and ultimately lysed to release the new viral particles.
A large, non-specific, phagocytic cell of the immune system.
frequently leave the bloodstream to crawl around in the tissues and perform "clean up" duties, such as ingesting dead cells or cellular debris at an injury site, or pathogens.
6.2 and 9.4
The cells of the distal tubule at the juxtaglomerular apparatus.
They are receptors that monitor filtrate osmolarity as a means of regulating filtration rate.
If drop in osmolarity is sensed, the macula densa dilates the afferent arteriole (to increase blood pressure in the glomerulus and thus increase filtration) and stimulates the juxtaglomerular cells to secrete renin (to raise systemic blood pressure).
Genes that are inherited only from the mother, such as mitochondrial genes (all of a zygote's organelles come only from the ovum).
A sensory receptor that responds to mechanical disturbances, such as shape changes (being squashed, bent, pulled, etc.)
include touch receptors in the skin, hair cells in the ear, muscle spindles, and others.
The environment in which or upon which bacteria grow.
typically contains a sugar source and any other nutrients that bacteria may require
"Minimal medium" contains nothing but glucose.
The inner region of an organ, e.g., the renal medulla, the ovarian medulla, the adrenal medulla, etc.
8.4 and 10.2
The portion of the hindbrain that controls respiratory rate and blood pressure, and specialized digestive and respiratory functions such as vomiting, sneezing, and coughing.
A type of cell division (in diploid cells) that reduces the number of chromosomes by half.
usually produces haploid gametes in organisms that undergo sexual reproduction.
It consists of a single interphase (G1, S, G2) followed by two sets of chromosomal divisions: meiosis 1 and meiosis 2.
Meiosis 1 and 2 can both be subdivided into four phases similar to those in mitosis.
A pigment produced by melanocytes in the bottom cell layer of the epidermis.
production is increased on exposure to UV radiation (commonly called "tanning" and helps prevent cellular damage due to UV radiation.
A cell produced when a B cell is activated by antigen.
do not actively fight the current infection with the same antigen.
If the antigen should appear again in the future, memory cells are like "pre-activated" B cells, and can initiate a much faster immune response (the secondary immune response).
The protective, connective tissue wrappings of the central nervous system (the dura mater, arachnoid mater, and pia mater).
The period of time in a woman's life when ovulation and menstruation cease.
typically begins in the late 40s.
The first phase of the uterine (endometrial) cycle, during which the unused endometrium from the previous cycle is shed off.
Estrogen and progesterone levels are low during this time period.
typically lasts from day 1 to day 5 of the cycle.
One of the three primary (embryonic) germ layers formed during gastrulation.
ultimately forms "middle" structures such as the bones, muscles, blood vessels, heart, kidneys, etc.
The second phase of mitosis.
replicated chromosomes align at the center of the cells (the metaphase plate)
The second phase of meiosis 1.
paired homologous chromosomes (tetrads) align at the center of the cell (the metaphase plate).
The second phase of meiosis 2.
identical to mitotic metaphase, except that the number of chromosomes was reduced by half during meiosis 1.
AKA Major histocompatibility complex
a set of proteins found on the plasma membranes of cells that help display antigen to T cells.
MHC 1 is found on all cells and displays bits of proteins from within the cell;
this allows T cells to monitor cell contents and if abnormal peptides are displayed on the surface, the cell is destroyed by killer T cells.
MHC 2 is found only on macrophages and B cells.
This class of MHC allows these cells (known as antigen presenting cells) to display bits of "eaten" (phagocytosed or internalized) proteins on their surface, allowing the activation of helper Ts.
The cytoskeleton filaments with the smallest diameter.
composed of the contractile protein actin.
dynamic filaments, constantly being made and broken down as needed, and are responsible for events such as pseudopod formation and cytokinesis during mitosis.
The largest of the cytoplasmic filaments.
composed of two types of protein, a-tubulin and B-tubulin.
They are dynamic fibers, constantly being built up and broken down, according to cellular needs.
form the mitotic spindle during cell division
form the base of cilia and flagella
used for intracellular structure and transport.
Microscopic outward folds of the cells lining the small intestine
serve to increase the surface area of the small intestine for absorption.
The portion of the brain responsible for visual and auditory startle reflexes.
The release of milk from the mammary glands via contraction of ducts within the glands.
Contraction is stimulated by oxytocin, which is released from posterior pituitary when the baby begins nursing.
A point mutation in which a codon that specifies an amino acid is mutated into a codon that specifies a different amino acid.
An organelle surrounded by a double membrane (two lipid bilayers) where ATP production takes place.
The interior (matrix) is where PDC and the Krebs cycle occur
the inner membrane contains the enzymes of the electron transport chain and ATP synthase.
The phase of the cell cycle during which the replicated genome is divided.
Mitosis has four phases (prophase, metaphase, anaphase, telophase)
includes cytokinesis (the physical splitting of the cell into two new cells).
See "atrioventricular valve."
mRNA that codes for a single type of protein, such as is found in eukaryotic cells.
The building blocks (monomers) of carbohydrates.
Monosaccharides have the chemical formula CnH2nOn.
Common monosaccharides are glucose, fructose, galactose, ribose, and deoxyribose.
A solid clump of cells resulting from cleavage in the early embryo.
Because there is very little growth of these cells during cleavage, the morula is only about as large as the original zygote
motor end plate
The portion of the muscle cell membrane at the neuromuscular junction;
essentially the postsynaptic membrane at this synapse.
A motor neuron and all the skeletal muscle cells it innervates.
Large motor units are typically found in large muscles (e.g., the thighs and buttocks) and produce gross movements.
Small motor units are found in smaller muscles (e.g., the rectus muscles that control movements of the eyeball, the fingers) and produce more precise movements.
motor unit recruitment
A mechanism for increasing tension (contractile strength) in a muscle by activating more motor units.
Messenger RNA; the type of RNA that is read by a ribosome to synthesize protein.
The monitoring of mRNA transcripts to eliminate those that are defective (e.g., have no stop codon, have premature stop codons, or that have somehow stalled in translation)
The layer of ciliated, mucus-covered cells in the respiratory tract.
The cilia continually beat, sweeping contaminated mucus upward toward the pharynx.
6.5 and 12.1
The layer of epithelial tissue that lines body cavities in contact with the outside environment (respiratory, digestive, urinary, and reproductive tracts)
Early embryonic ducts that can develop into female internal genitalia in the absence of testosterone.
Müllerian inhibiting factor (MIF)
A substance secreted by embryonic testes that causes the regression of the Müllerian ducts.
A neuron with a single axon and multiple dendrites, the most common type of neuron in the nervous system.
An insulating layer of membranes wrapped around the axons of almost all neurons in the body.
essentially the plasma membranes of specialized cells;
Schwann cells in the peripheral nervous system, and oligodendrocytes in the central nervous system.
A network of neurons between the circular and longitudinal muscle layers in the gut;
it helps regulate gut motility.
Part of the enteric nervous system.
A skeletal muscle cell, also known as a muscle fiber.
Skeletal muscle cells are formed from the fusion of many smaller cells (during development) consequently they are very long and are multinucleate.
A string of sarcomeres within a skeletal muscle cell.
Each muscle cell contains hundreds of myofibrils
A globular protein found in muscle tissue that has the ability to bind oxygen.
helps to store oxygen in the muscle for use in aerobic respiration.
Muscles that participate in endurance activities (including cardiac muscle) have abundant supplies of myoglobin.
The muscular layer of the uterus.
made of smooth muscle that retains its ability to divide in order to accommodate the massive size increases that occur during pregnancy.
stimulated to contract during labor by the hormone oxytocin
One of the contractile proteins in muscle tissue.
In skeletal and cardiac muscle, myosin form the thick filaments.
has intrinsic ATPase activity and can exist in two conformations, either high energy or low energy.
myosin light-chain kinase (MLCK)
A kinase in smooth muscle cells activated by calmodulin in the presence of Ca2+.
this kinase phosphorylates myosin, activating it so that muscle contraction can occur.
A protein found in the plasma membranes of all cells in the body that uses the energy of an ATP (hydrolyzes ATP)
to move three Na+ ions out of the cell and two K+ ions into the cell,
thus establishing concentration gradients for these ions across the cell membrane.
The mechanism described by Charles Darwin that drives evolution.
Through mutation some organisms possess genes that make them better adapted to their environment.
These organisms survive and reproduce more than those that do not possess the beneficial genes, thus these genes are passed on to offspring, making the offspring better adapted.
Over time, these genes (and the organisms that possess them) become more abundant, and the less beneficial genes (and the organisms that possess them) become less abundant.
ncRNA (non-coding RNA)
RNA that is not translated into protein, including tRNA, rRNA, snRNA, miRNA, etc.
A form of regulation in which the end result of a series of events inhibits the trigger for that series
Hormones are generally regulated via negative feedback
For example, insulin is released when blood glucose levels rise.
It causes the cells of the body to take glucose out of the blood, leading to a drop in glucose levels
The fall in glucose levels stops insulin release
The functional unit of the kidney.
Each kidney has about a million nephrons; this is where blood filtration and subsequent modification of the filtrate occurs.
The nephron empties into collecting ducts, which empty into the ureter.
The equation that can predict the equilibrium potential for any ion based on the electrochemical gradients for that ion across the membrane.
Cells that separate from the neural tube during neurulation and migrate to different parts of the embryo.
Neural crest cells differentiate into a variety of cell types, including melanocytes, glial cells, the adrenal medulla, some peripheral neurons and some facial connective tissue.
See "posterior pituitory gland."
neuromuscular junction (NMJ)
The synapse between a motor neuron and muscle cell.
At the NMJ, the muscle cell membrane is invaginated and the axon terminus is elongated so that a greater area of membrane can be depolarized at one time.
8.2 and 11.2
The basic functional and structural unit of the nervous system.
a highly specialized cell, designed to transmit action potentials.
A chemical released by the axon of a neuron in response to an action potential that binds to receptors on a postsynaptic cell and causes that cell to either depolarize slightly (EPSP) or hyperpolarize slightly (IPSP).
Examples are acetylcholine, norepinephrine, GABA, dopamine, and others.
The formation of the nervous system during weeks 5-8 of gestation.
begins when a section of the ectoderm invaginates and pinches off to form the neural tube, from which the brain and spinal cord develop.
AKA Pain receptors.
found everywhere in the body except for the brain.
nodes of Ranvier
Gaps in the myelin sheath of the axons of peripheral neurons.
Action potentials can "jump" from node to node, thus increasing the speed of conduction (saltatory conduction).
The failure of homologous chromosomes or sister chromatids to separate properly during cell division.
This could occur during anaphase 1 of meiosis (homologous chromosomes), or during anaphase 2 of meiosis or anaphase of mitosis (sister chromatids).
A point mutation in which a codon that specifies an amino acid is mutated into a stop (nonsense) codon
The neurotransmitter used by the sympathetic division of the ANS at the post-ganglionic (organ-level) synapse.
The double lipid bilayer that surrounds the DNA in eukaryotic cells.
nuclear localization sequence
A sequence of amino acids that directs a protein to the nuclear envelope, where it is imported by a specific transport mechanism.
A protein within the nucleus where rRNA is transcribed and ribosomes are partially assembled.
"A protein channel in the nuclear envelope that allows the free passage of molecules smaller than 60 kD"
A region within the nucleus where rRNA is transcribed and ribosomes are partially assembled
A structure composed of a ribose molecule linked to one of the aromatic bases.
In a deoxynucleoside, the ribose is replaced with deoxyribose.
A structure composed of two coils of DNA wrapped around an octet of histone proteins.
the primary form of packaging of eukaryotic DNA
A nucleoside with one or more phosphate groups attached. Nucleoside triphosphates (NTPs) are the building blocks of RNA and are also used as energy molecules, especially ATP.
Deoxynucleoside triphosphates (dNTPs) are the building blocks of DNA; in these molecules, the ribose is replaced with deoxyribose.
An organelle bounded by a double membrane (double lipid bilayer) called the nuclear envelope.
contains the genome and is the site of replication and transcription.
An organism that requires oxygen to survive (aerobic metabolism only)
An organism that can only survive in the absence of oxygen (anaerobic metabolism);
oxygen is toxic to obligate anaerobes.
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
Chemoreceptors in the upper nasal cavity that respond to odor chemicals.
Mutated genes that cause cancer.
Proto-oncogenes are the normal version of these genes before their mutations.
The osmotic pressure in the blood vessels due only to plasma proteins (primarily albumin).
A precursor cell that undergoes mitosis during fetal development to produce more oogonium.
These cells are the activated to produce primary oocytes, which remain dormant until stimulated to undergo meiosis 1 during some future menstrual cycle.
A specific DNA nucleotide sequence where transcriptional regulatory protein can bind.
A nucleotide sequence on DNA that contains three elements:
•a coding sequence for one or more enzymes
•a coding sequence for a regulatory protein
•upstream regulatory sequences where the regulatory protein can bind.
An example is the lac operon found in prokaryotes.
The "blind spot" of the eye, this is where the axons of the ganglion cells exit the retina to form the optic nerve.
There are no photoreceptors in the optic disk.
The nerve extending from the back of the eyeball to the brain that carries visual information.
made up of the axons of the ganglion cells of the retina.
organ of Corti
The structure in the cochlea of the inner ear made up of the basilar membrane, the auditory hair cells, and the tectorial membrane.
the site where auditory sensation is detected and transduced to action potentials.
The stage of human development during which the organs are formed.
begins after gastrulation and is completed by the 8th week of gestation.
A function of the reproductive system controlled by the sympathetic nervous system.
In males, orgasm includes emission and ejaculation
in females it is mainly a series of rhythmic contractions of the pelvic floor muscles and the uterus.
origin of replication
The specific location on a DNA strand where replication begins.
Prokaryotes typically have a single origin of replication
while eukaryotes have several per chromosome.
The movement of water (the solvent) from its region of high concentration to its region of low concentration.
Note that the water concentration gradient is opposite to the solute concentration gradient, since where solutes are concentrated, water is scarce.
The force required to resist the movement of water by osmosis.
essentially a measure of the concentration of a solution.
A solution that is highly concentrated has a strong tendency to draw water into itself, so the pressure required to resist that movement would be high.
Thus, highly concentrated solutions are said to have high osmotic pressures.
The three small bones found in the middle ear (the malleus, the incus, and the stapes) that help to amplify the vibrations from sound waves.
The malleus is attached to the tympanic membrane and the stapes is attached to the oval window of the cochlea.
A cell that produces bone.
A phagocytic-like bone cell that breaks down bone matrix to release calcium and phosphate into the bloodstream.
A mature, dormant osteoblast.
The unit of compact bone, formerly called a Haversion system.
essentially long cylinders of bone
the hollow center is called the central canal, and is where blood vessels, nerves, and lymphatic vessels are found.
Compact bone is laid down around the central canal in rings (lamellae).
The portion of the ear consisting of the pinna and the external auditory canal.
separated from the middle ear by the tympanic membrane (the eardrum)
The membrane that separates the middle ear from the inner ear.
The 28 days of the menstrual cycle as they apply to events in the ovary.
has three sub-phases:
•the follicular phase
The female primary sex organ.
produces female gametes (ova) and secretes estrogen and progesterone.
The release of a secondary oocyte (along with some granulosa cells) from the ovary at the approximate midpoint of the menstrual cycle (typically around day 14).
triggered by a surge in LH.
A hormone released by the posterior pituitary that stimulates uterine contractions during childbirth and milk ejection during breastfeeding.
8.6 and 13.14
A self-initiating action potential that occurs in the conduction system of the heart and triggers action potentials (and thus contraction) in the cardiac muscle cells.
triggered by the regular, spontaneous depolarization of the cells of the conduction system, due to a slow inward leak of positive ions (Na+ and Ca2+).
Because the SA node has the fastest leak, it typically reaches the threshold for the pacemaker potential before any other region of the conduction system, and thus sets the pace of the heart.
An organ in the abdominal cavity with two roles.
The first is an exocrine role: to produce digestive enzymes and bicarbonate, which are delivered to the small intestine via the pancreatic duct.
The second is an endocrine role: to secrete insulin and glucagon into the bloodstream to help regulate blood glucose levels.
The main duct of the pancreas.
carries the exocrine secretions of the pancreas (enzymes and bicarbonate) to the small intestine (duodenum).
An organism that requires the aid of a host organism to survive
harms the host in the process.
parasympathetic nervous system
AKA the craniosacral system because the pre-ganglionic neurons all originate from either the brain or the sacrum
The division of the autonomic nervous system known as the "resting and digesting" system.
causes a general decrease in body activities such as:
an increase in:
•blood flow to the GI tract
parathyroid hormone (PTH)
A hormone produced and secreted by the parathyroid glands that increases serum calcium levels.
•the bones (stimulates osteoclasts)
•the kidneys (increases calcium reabsorption)
•the small intestine (increases calcium absorption).
Cells found in gastric glands that secrete:
•hydrochloric acid (for hydrolysis of ingested food)
•gastric intrinsic factor (for absorption of vitamin B12).
The contribution of an individual gas to the total pressure of a mixture of gases.
used to describe the amounts of the various gases carried in the bloodstream.
Movement across the membrane of a cell that does not require energy input from the cell.
relies on concentration gradients to provide the driving force for movement
includes both simple and facilitated diffusion.
The percentage of individuals with a particular genotype that actually display the phenotype associated with that genotype.
The second step in viral infection
the injection of the viral genome into the host cell.
A protein-digesting enzyme secreted by the chief cells of the gastric glands.
secreted in its inactive form (pepsinogen) and is activated by gastric acid.
It is unusual in that its pH optimum is around 1-2
most of the enzymes in the body function best at neutral pHs.
A hormone made of amino acids (in some cases just a single, modified amino acid).
generally hydrophilic and cannot cross the plasma membranes of cells, thus receptors for peptide hormones must be found on the cell surface.
An exception is thyroxine, which is hydrophobic enough to enter the cells easily.
Binding of a peptide hormone to its receptor usually triggers a second messenger system within the cell.
A complex polymer of sugars and amino acids
the substance from which bacterial cell walls are made.
The enzymatic activity of the ribosome that catalyzes the formation of a peptide bond between amino acids.
It is thought that the rRNA of the ribosome possesses the peptidyl transferase activity.
The flow of blood through a tissue.
Receptors in the carotid arteries and the aorta that monitor blood pH to help ventilation rate.
peripheral membrane protein
A protein that is associated with the plasma membrane of a cell, but that is not embedded in the lipid bilayer.
typically associate with embedded proteins through hydrogen bonding or electrostatic interaction.
peripheral nervous system
All parts of the nervous system except for the brain and spinal cord.
The resistance to blood flow in the systemic circulation.
increases if arteries constrict (diameter decreases)
an increase in peripheral resistance leads to an increase in blood pressure.
The space between the inner and outer cell membranes in Gram-negative bacteria.
The peptidoglycan cell wall is found in the periplasmic space, and this space sometimes contain enzymes to degrade antibiotics.
A wave of contraction that sweeps along a muscular tube, pushing substances along the tube
(e.g., food through the digestive tract, urine through the ureters etc.)
Small organelles that contain hydrogen peroxide produced as a byproduct of lipid metabolism.
convert hydrogen peroxide to water and oxygen by way of the enzyme catalase.
The non-specific uptake of solid material by a cell accomplished by engulfing the particle with plasma membrane and drawing it into the cell.
A passageway leading from behind the nasal cavity to the trachea.
divided into three regions, named for their location.
•The nasopharynx is behind the nasal cavity, a passageway for air only
•the oropharynx is behind the oral cavity, a passageway for both air and food
•the laryngopharynx is behind the larynx, a passageway for both air and food
consequently they are lined with a much thicker layer of cells to resist damage due to abrasion.
10.6 and 12.2
The physical characteristics resulting from the genotype.
usually described as dominant or recessive.
Chemical signals released from one organism that result in a social response in membranes of the same species.
The primary membrane lipid.
consists of a glycerol molecule esterified to two fatty acid chains and a phosphate molecule.
Additional, highly hydrophilic groups are attached to the phosphate, making this molecule extremely amphipathic
3.4 and 6.3
A receptor that responds to light.
An organism that utilizes light as its primary energy source.
A long projection on a bacterial surface involved in attachment
e.g, the sex pilus attaches F+ and F- bacteria during conjugation.
The non-specific uptake of liquid particles into a cell by invagination of the plasma membrane and subsequent "pinching off" of a small bit of the extracellular fluid.
An organ that develops during pregnancy, derived in part from the mother and in part from the zygote.
the site of exchange of nutrients and gases between the mother's blood and the fetus' blood.
formed during the first three months of pregnancy.
Zygote-derived projections that extend into the endometrium of the uterus during pregnancy.
Fetal capillaries grow into the placental villi, which are surrounded by a pool of maternal blood.
This facilitates nutrient and gas exchange between the mother and the fetus, without actually allowing the bloods to mix.
A clear area in a lawn of bacteria.
Plaques represent an area where bacteria are lysing (dying) and a usually caused by lytic viruses.
The liquid portion of blood;
contains water, ions, buffers, sugars, proteins, etc.
Anything that dissolves in blood dissolves in the plasma portion.
An activated B cell that is secreting antibody.
A small, extrachromosomal (outside the genome), circular DNA molecule found in prokaryotes.
5.3 and A.5
Extremely small pseudo-cells in the blood, important for clotting.
They are not true cells, but are broken-off bits of a larger cell (a megakaryocyte).
The membranes that line the surface of the lungs (visceral pleura) and the inside wall of the chest cavity (parietal pleura).
The pressure in the (theoretical) space between the lung surface and the inner wall of the chest cavity.
negative with respect to atmospheric pressure
this keep the lungs stuck to the chest cavity wall.
A type of mutation in DNA where a single base is substituted for another.
A small cell with extremely little cytoplasm that results from the unequal cytoplasmic division of the primary (produces the first polar body) and secondary (produces the second polar body) oocytes during meiosis (oogenesis).
The polar bodies degenerate.
A string of several hundred adenine nucleotides added to the 3' end of eukaryotic mRNA.
mRNA that codes for several different proteins by utilizing different reading frames, nested genes, etc.
a characteristic of prokaryotes.
A class of enzymes that polymerizes macromolecules, e.g.,DNA polymerase.
polymerase chain reaction (PCR)
A very quick and inexpensive method for detecting and amplifying specific DNA sequences.
the fertilization of an oocyte by more than one sperm
occurs in some animals, but in humans, blocks to polyspermy exist (the fast block and the slow block) so that only a single sperm can penetrate the oocyte
A subset of a species consisting of members that mate and reproduce with one another.
A pathway through a plasma membrane that restricts passage based only on the size of the molecule.
made from porin proteins.
A system of blood vessels where the blood passes from arteries to capillaries to veins, then through a second set of capillaries, and then through a final set of veins.
There are two portal systems in the body:
•the hepatic portal system
•the hypothalamic portal system.
posterior pituitory gland
made of nervous tissue (i.e., neurons) and stores and secretes two hormones made by hypothalamus; oxytocin and ADH.
controlled by action potential from the hypothalamus.
In the autonomic division of the PNS, a neuron that has its cell body located in an autonomic ganglion (where a pre-ganglionic neuron synapses with it), and whose axon synapses with the target organ.
potassium leak channel
An ion channel specific for potassium found in the plasma membrane of all cells in the body.
Leak channels are constitutively open and allow their specific ion to move across the membrane according to its gradient.
Potassium leak channels allow potassium to leave the cell.
The step in the sliding filament theory during which myosin undergoes a conformational change to its low energy state, in the process dragging the thin filaments (and the attached Z lines) toward the center of the sarcomere.
Note that the power stroke requires ATP only indirectly: to set the myosin molecule in its high-energy conformation during a different step of the sliding filament theory.
In the autonomic division of the PNS, a neuron that has its cell body located in the CNS, and whose axon extends into the PNS to synapse with a second neuron at an autonomic ganglion. (The second neuron's axon synapses with the target organ.)
primary active transport
Active transport that relies directly on the hydrolysis of ATP.
The first branches off the trachea.
There are two primary bronchi, one for each lung.
primary immune response
The first encounter with an antigen, resulting in activated B cells (for antibody secretion) and T cells (for cellular lysis and lymphocyte proliferation).
takes approximately ten days, which is long enough for symptoms of the infection to appear.
Diploid cells resulting from the activation of an oogonium;
ready to enter meiosis 1.
Diploid cells resulting from the activation of spermatogonium;
ready to enter meiosis 1.
An RNA polymerase that creates a primer (made of RNA) to initiate DNA replication.
DNA pol binds to the primer and elongates it.
Mis-folded, self-replicating proteins responsible for a class of diseases known as transmissible spongiform encephalopathies (TSEs) that cause degeneration of CHS tissues.
A life cycle of animal viruses in which the mature viral particles bud from the host cell, acquiring an envelope (a coating of lipid bilayer) in the process.
A steroid hormone produced by the corpus luteum in the ovary during the second half of the menstrual cycle.
maintains and enhances the uterine lining for the possible implantation of fertilized ovum.
It is the primary hormone secreted during pregnancy.
An organism that lacks a nucleus or any other membrane-bound organelles.
All prokaryotes belong to either Domain Bacteria or Domain Archaea (formerly Kingdom Monera).
A hormone secreted by the anterior pituitary that targets the mammary glands, stimulating them to produce breast milk.
The second phase of the uterine (endometrial) cycle, during which the endometrium (shed off during menstruation) is rebuilt.
This phase of the cycle is under the control of estrogen, secreted from the follicle developing in the ovary during this time period.
The proliferative phase typically lasts from day 6 to day 14 of the menstrual cycle.
The sequence of nucleotides on a chromosome that activates RNA polymerase so that transcription can take place.
found upstream of the start site, the location where transcription actually begins.
The first phase of mitosis.
the replicated chromosomes condense, the spindle is formed, and the nuclear envelope breaks apart into vesicles.
The first phase of meiosis 1.
•the replicated chromosomes condense
•homologous chromosomes pair up
•crossing over occurs between homologous chromosomes
•the spindle is formed
•the nuclear envelope breaks apart into vesicles.
Prophase 1 is the longest phase of meiosis.
The first phase of meiosis 2.
identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis 1.
A receptor that responds to change in body position, such as stretch on a tendon, or contraction of a muscle.
These receptors allow us to be consciously aware of the position of our body parts.
A small gland encircling the male urethra just inferior to the bladder
Its secretions contain nutrients and enzymes and account for approximately 35% of the ejaculate volume.
A non-protein, but organic, molecule (such as a vitamin) that is covalently bound to an enzyme as part of the active site.
10.5 and 10.9
proximal convoluted tubule (PCT)
The first portion of the nephron tubule after the glomerulus.
the site of most reabsorption
all filtered nutrients are reabsorbed here as well as most of the filtered water.
the site on a ribosome where the growing peptide (attached to a tRNA) is found during translation.
Salivary amylase (see "amylase")
The blood vessel that carries deoxygenated blood from the right ventricle of the heart to the lungs.
The flow of blood from the heart, through the lungs and back of the heart.
A collection of fluid in the alveoli of the lungs, particularly dangerous because it impedes gas exchange.
Common causes of pulmonary edema are increased pulmonary blood pressure or infection in the respiratory system
One of the several vessels that carry oxygenated blood from the lungs to the left atrium of the heart.
A hole in the center of the iris of the eye that allows light to enter the eyeball.
The diameter of the pupil is controlled by the iris in response to the brightness of the light.
Aromatic bases found in DNA and RNA that are derived from purine.
They have a double-ring structure and include adenine and guanine.
The smallest (and final) fibers in the cardiac conduction system.
transmit the cardiac impulse to the ventricular muscle.
The valve that regulates the passage of chyme from the stomach into the small intestine.
Aromatic bases found in DNA and RNA that have a single-ring structure.
They include cytosine, thymine, and uracil.
RIAs are similar to ELISAs but use radio-labeled antibodies rather than enzyme-linked antibodies.
Thus, the presence of target proteins or antibodies is assayed by measuring the amount of radioactivity instead of a color change.
A highly specific cellular uptake mechanism.
The molecule to be taken up must bind to a cell surface receptor found in a clathrin-coated pit.
The allele in a heterozygous genotype that is not expressed;
the phenotype resulting from possession of two recessive alleles (homozygous recessive).
recombination frequency (RF)
AKA The RF value;
the percentage of recombinant offspring resulting from a given genetic cross.
proportional to the physical distance between two genes on the same chromosome.
If the recombination frequency is low, the genes under consideration may be linked.
The tight regulatory control exerted over opposing metabolic pathways in order to avoid futile.
The final portion of the large intestine.
red slow twitch fibers
Skeletal muscle cells that contract slowly but are fatigue resistant due to a high concentration of myoglobin and a good blood supply.
A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus, often without conscious brain involvement.
relative refractory period
The period of time following an action potential when it is possible, but difficult, for the neuron to fire a second action potential, due to the fact that the membrane is further from threshold potential (hyperpolarized).
A cytoplasmic protein that binds to a stop codon when it appears in the A-site of the ribosome.
modify the peptidyl transferase activity of the ribosome, such that a water molecule is added to the end of the completed protein.
This releases the finished protein from the final tRNA, and allows the ribosome subunits and mRNA to dissociate.
The movement of a substance from the filtrate (in the renal tubule) back into the bloodstream.
reduces the amount of a substance in the urine.
The portion of the nephron after the glomerulus and capsule
the region of the nephron where the filtrate is modified along its path to becoming urine.
An enzyme secreted by the juxtaglomerular cells when blood pressure decreases.
Renin converts angiotensinogen to angiotensin 1.
The duplication of DNA.
The site(s) where the parental DNA double helix unwinds during replication.
Multiple sites of replication found on large ,linear eukaryotic chromosomes.
The return of membrane potential to normal resting values after a depolarization or hyperpolarization.
A system (set of genes) where the expression of those genes is inhibited by the gene product
(e.g., the trp operon).
A regulatory protein that binds DNA at a specific nucleotide sequence (sometimes known as the operator) to prevent transcription of downstream genes.
The volume of air remaining in the lungs after a maximal forced exhalation, typically about 1200 mL
A function of the reproduction system (controlled by the sympathetic nervous system) that returns the body to its normal resting state after sexual arousal and orgasm.
A drop in blood pH due to hypoventilation (too little breathing) and a resulting accumulation of CO2.
A rise in blood pH due to hyperventilation (excessive breathing) and a resulting decrease in CO2.
resting membrane potential
An electrical potential established across the plasma membrane of all cells by the Na+/K+ leak channels.
In most cells, the resting membrane potential is approximately -70 mV with respect to the outside of the cell.
A bacterial enzyme that recognizes a specific DNA nucleotide sequence and that cuts the double helix at a specific site within that sequence.
The innermost layer of the eyeball.
made up of a layer of photoreceptors, a layer of bipolar cells, and a layer of ganglion cells.
A chemical derived from vitamin A found in the pigment proteins of the rod photoreceptors of the retina.
changes conformation when it absorbs light, triggering a series of reactions that ultimately result in an action potential being sent to the brain.
A virus with an RNA genome (e.g., HIV) that undergoes a lysogenic life cycle in a host with a double-stranded DNA genome.
In order to integrate its genome with the host cell genome, the virus must first reverse-transcribe its RNA genome to DNA.
An enzyme that polymerizes a strand of DNA by reading an RNA template (an RNA dependent DNA polymerase)
used by retroviruses in order to integrate their genome with the host cell genome.
A structure made of two protein subunits and rRNA
this is the site of protein synthesis (translation) in a cell.
Prokaryotic ribosomes (also known as 70S ribosome) are smaller than eukaryotic ribosomes (80S ribosomes).
The S value refers to the sedimentation rate during centrifugation.
RNA-dependent RNA polymerase
A viral enzyme that makes a strand of RNA by reading a strand of RNA.
All prokaryotic and eukaryotic RNA polymerases are DNA dependent
they make a strand of RNA by reading a strand of DNA.
RNA interference (RNAi)
Small non-coding RNAs that bind to mRNAs
these double-stranded RNAs are then degraded and gene expression is reduced.
An enzyme that transcribes RNA
Prokaryotes have a single RNA pol
eukaryotes have three; in eukaryotes:
•RNA pol 1 transcribes rRNA
•RNA pol 2 transcribes mRNA
•RNA pol 3 transcribes tRNA.
The movement of new mRNA transcripts to particular locations within the cell prior to their translation.
Photoreceptors in the retina of the eye that respond to dim light and provide us with black and white vision.
rough endoplasmic reticulum
A large system of folded membrane within a eukaryotic cell that has ribosomes bound to it, giving it a rough appearance.
These ribosomes synthesize proteins that will ultimately be secreted from the cell, incorporated into the plasma membrane, or transported to the Golgi apparatus or lysosomes.
AKA Ribosomal RNA
the type of RNA that associates with ribosomal positions to make a functional ribosome.
It is thought that the rRNA has the peptidyl transferase activity.
rule of addition
A statistical rule stating that the probability of EITHER OF TWO independent (and mutually exclusive) events occurring is the sum of their individual probabilities.
rule of multiplication
A statistical rule stating that the probability of TWO independent events occurring TOGETHER is the product of their individual probabilities.
A rapid form of action potential conduction along the axon of a neuron in which the action potential appears to jump from node of Ranvier to node of Ranvier.
The plasma membrane of a muscle cell.
The unit of muscle contraction.
bounded by Z lines, to which thin filaments attach.
Thick filaments are found in the center of the sarcomere, overlapped by thin filaments.
Sliding of the filaments over one another during contraction reduces the distance between Z lines, shortening the sarcomere.
sarcoplasmic reticulum (SR)
The smooth ER of a muscle cell, enlarged and specialized to act as a Ca2+ reservoir.
The SR winds around each myofibril in the muscle cell.
One of the two peripheral nervous system supporting (glial) cells.
form the myelin sheath on axons of peripheral neurons.
The white portion of the tough outer layer of the eyeball.
Oil-forming glands found all over the body, especially on the face and neck.
The product (sebum) is released to the skin surface through hair follicles.
secondary active transport
Active transport that relies on an established concentration gradient, typically set up by a primary active transporter.
relies on ATP indirectly.
secondary immune response
A subsequent immune response to previously-encountered antigen that results in antibody production and T cell activation.
mediated by memory cells (produced during the primary immune response) and is much faster and stronger than the primary response,
typically taking only a day or less.
This is not long enough for the infection to become established;
symptoms do not appear, thus the person is said to be "immune" to that particular antigen.
A haploid cell resulting from the first meiotic division of oogenesis.
Note that the cytoplasmic division in this case is unequal, producing one large cell with almost all of the cytoplasm (the secondary oocyte) and one smaller cell with virtually no cytoplasm (the first polar body).
The secondary oocyte, along with some follicular cells, is released from the ovary during ovulation.
secondary sex characteristics
The set of adult characteristics that develop during puberty under the control of the sex steroids.
In males the secondary sex characteristics include enlargement and maturation of the genitalia, growth of facial, body, and pubic hair, increased muscle mass, and lowering of the voice.
In females, the characteristics include the onset of menstruation and the menstrual cycle, enlargement of the breasts, widening of the pelvis, and growth of pubic hair
Haploid cells resulting from the first meiotic division of spermatogenesis.
Secondary spermatocytes are ready to enter meiosis 2.
An intracellular chemical signal (such as cAMP) that relays instructions from the cell surface to enzymes in the cytosol.
A hormone secreted by the small intestine (duodenum) in response to low pH (e.g., from stomach acid).
It promotes the release of bicarbonate from the pancreas to act as a buffer.
1. The secretion of useful substances from a cell, either into the blood (endocrine secretion) or into a cavity or onto the body surface (exocrine secretion).
2. In the nephron, the movement of substances from the blood to the filtrate along the tubule. Secretion increases the rate at which substances can be removed from the body.
10.2 and 10.5
The third phase of the uterine (endometrial) cycle, during which the rebuilt endometrium is enhanced with glycogen and lipid stores.
The secretory phase is primarily under the control of progesterone and estrogen (secreted from the corpus luteum during this time period)
typically lasts fro day 15 to day 28 of the menstrual cycle.
An alkaline, fructose-rich fluid produced by three different glands in the male reproductive tract and released during ejaculation.
Semen is very nourishing for sperm.
Three loop-like structures in the inner ear that contain sensory receptors to monitor balance.
AKA method for DNA replication.
Each of the parental strands is read to make a complementary daughter strand, thus each new DNA molecule is composed of half the parental molecule paired with a newly synthesized strand.
The valves in the heart that separates the ventricles from the arteries.
The pulmonary semilunar valve separates the right ventricle from the pulmonary artery
the aortic semilunar valve separates the left ventricle from the aorta.
These valves close at the end of systole, preventing the back-flow of blood from arteries to ventricle, and producing the second heart sound.
Paired glands found on the posterior external wall of the bladder in males.
Their secretions contain all alkaline mucus and fructose, among other things, and make up approximately 60% of the ejaculate volume.
small convoluted tubules in the testes where spermatogenesis takes place.
The process of biological aging at the cellular (and organismal) level
See "sustenacular cells."
Plasma with the clotting factors removed.
Serum is often used in diagnostic tests since it does not clot.
A trait determined by a gene or either the X or the Y chromosomes (the sex chromosomes).
The prokaryotic ribosome-binding site on mRNA
found 10 nucleotides 5' to the start codon.
signal detection theory
attempts to predict how and when someone will detect the presence of a given sensory stimulus (the "signal") amidst all of the other sensory stimuli in the background ( the "noise").
signal recognition particle (SRP)
A cytoplasmic protein that recognizes the signal sequences of proteins destined to be translated at the rough ER.
It binds first to the ribosome translating the protein with the signal sequence, then to an SRP receptor on the rough ER.
A short sequence of amino acids, usually found at the N-terminus of a protein being translated that directs the ribosome and its associated mRNA to the membranes of the rough ER where translation will be completed.
found on membrane-bound proteins, secreted proteins, and proteins destined for other organelles.
The intracellular process triggered by the binding of a ligand to its receptor on the cell surface.
Typically this activates second messenger pathways.
A point mutation in which a codon that specifies an amino acid is mutated into a new codon that specifies the same amino acid.
The movement of a hydrophobic molecule across the plasma membrane of cell, down its concentration gradient.
Since the molecule can easily interact with the lipid bilayer, no additional help (such as a channel or pore) is required.
single nucleotide polymorphisms (SNPs)
Variations in a single nucleotide from one person's DNA gene sequence to another's.
These minor mutations can produce changes in phenotype.
single strand binding proteins
Proteins that bind to and stabilize the single strands of DNA exposed when helicase unwinds the double helix in preparation for replication.
sinoatrial (SA) node
A region of specialized cardiac muscle cells in the right atrium of the heart that initiate the impulse for heart contraction
for this reason the SA node is known as the "pacemaker" of the heart.
Identical copies of a chromosome, produced during DNA replication and held together at the centromere.
separated during anaphase of mitosis.
Muscle tissue that is attached to the bones.
striated, multinucleate, and under voluntary control.
sliding filament theory
The mechanism of contraction is skeletal and cardiac muscle cells.
It is a series of four repeated steps:
(1) myosin binds actin
(2) myosin pulls actin toward the center of the sarcomere
(3) myosin releases actin
(4) myosin resets to its high-energy conformation.
slow block to polyspermy
AKA the cortical reaction
the slow block occurs after a sperm penetrates an oocyte (fertilization).
It involves an increase in intracellular (Ca2+) in the egg, which causes the release of cortical granules near the egg plasma membrane.
This results in the hardening of the zona pellucida and its separation from the surface of the egg, preventing the further entry of more sperm into the egg.
The region of the digestive tract where virtually all digestion and absorption occur.
It is subdivided into three regions;
smooth endoplasmic reticulum
A network of membranes inside eukaryotic cells involved in:
•lipid synthesis (steroids in gonads)
•detoxification (in liver cells)
•Ca2+ storage (muscle cells)
Muscle tissue found in the walls of hollow organs
e.g., blood vessels, the digestive tract, the uterus, etc
smooth muscle is non-striated, uninucleate, and under involuntary control (controlled by the autonomic nervous system)
The cell body of a neuron.
somatic nervous system
AKA the voluntary nervous system
The division of the peripheral nervous system that innervates and control the skeletal muscles
Integration by a postsynaptic neuron of inputs (EPSPs and IPSPs) from multiple sources.
A haploid but immature cell resulting from the second meiotic division of spermatogenesis
undergo significant physical changes to become mature sperm (spermatozoa)
Sperm production production occurs in human males on a daily basis from puberty until death.
results in the production of four mature gametes (sperm) from a single precursor cell (spermatogenesis).
For maximum sperm viability, spermatogenesis requires cooler temperatures and adequate testosterone.
A diploid cell that can undergo mitosis to form more spermatogonium
can also be triggered to undergo meiosis to form sperm.
S (synthesis) phase
The phase of the cell cycle during which the genome is replicated.
4.4 and 6.6
sphincter of Oddi
The valve controlling release of bile and pancreatic juice into the duodenum.
A blood pressure cuff.
A bacterium having a spiral shape (plural = spirochetes).
An abdominal organ that is considered part of the immune system.
has four functions:
(1) it filters antigen from the blood
(2) it is the site of B cell maturation
(3) it stores blood
(4) it destroys old red blood cells.
A complex made of many proteins and several small nuclear RNAs (snRNAs) that assembles around an intron to be spliced out of the primary transcript.
One type of eukaryotic mRNA processing in which introns are removed from the primary transcript and exons are ligated together.
Splicing of transcripts can be different in different tissues.
A looser, more porous type of bone tissue found at the inner core of the epiphyses in long bones and all other bone types.
filled with red bone marrow, important in blood cell formation.
The location on a chromosome where transcription begins.
A hormone derived from cholesterol.
generally hydrophobic and can easily cross the plasma membranes of cells
thus receptors for steroids are found intracellularly.
Once the steroid binds to its receptor, the receptor-steroid complex acts to regulate transcription in the nucleus.
The portion of the digestive tract that stores and grinds food.
Limited digestion occurs in the stomach, and it has the lowest pH in the body (pH 1-2).
A group of three nucleotides that does not specify a particular amino acid, but instead serves to notify the ribosome that the protein being translated is complete.
The stop codons are UAA, UGA, and UAG.
They are also known as nonsense codons.
See "skeletal muscle."
The volume of blood pumped out of the heart in a single beat (contraction).
The layer of connective tissue directly under the mucosa of an open body cavity.
A network of neurons found in the submucosa of the gut;
it helps to regulate enzyme secretion, gut blood flow, and ion and water flow in the lumen.
Part of the enteric nervous system.
A sweat gland located in the dermis of the skin.
Sweat consists of water and ions (including Na+ and urea) and is secreted when temperatures rise.
(1.) The integration of input (EPSPs and IPSPs) from many presynaptic neurons by a single postsynaptic neuron, either temporally or spatially.
Summation of all input can either stimulate the postsynaptic neuron and possibly lead to an action potential
or it can inhibit the neuron, reducing the likelihood of an action potential.
(2.) The integration of single muscle twitches into a sustained contraction (tetany)
8.2 and 11.2
An amphipathic molecule secreted by cells in the alveoli (type 2 alveolar cells) that reduces surface tension on the inside of the alveolar walls.
This prevents the alveoli from collapsing upon exhale and sticking together, thus reducing the effort required for inspiration.
AKA Sertoli cells
Cells that form the walls of the seminiferous tubules and help in spermatogenesis.
respond to FSH.
Bacteria that coexist with a host, where both the bacteria and the host derive a benefit.
sympathetic nervous system
The division of the autonomic nervous system known as the "fight or flight" system.
It causes a general increase in body activities such as heart rate, respiratory rate, and blood pressure, and an increase in blood flow to skeletal muscle.
It causes a general decrease in digestive activity.
Because all of its pre-ganglionic neurons originate from the thoracic or lumbar regions of the spinal cord, it is AKA the thoracolumbar system.
A carrier protein that transports two molecules across the plasma membrane in the same direction.
For example, the Na+-glucose co-transporter in intestinal cells is a symporter.
A neuron-to-neuron, neuron-to-organ, or muscle cell-to-muscle cell junction.
Pairing of homologous chromosomes in a diploid cell, as occurs during prophase 1 of meiosis.
A microscopic space between the axon of one neuron and the cell body or dendrites of a second neuron or between the axon of a neuron and an organ.
A structure that forms in early prophase 1 that mediates synapsis (pairing of homologous chromosomes)
A large multinucleate cell
typically formed by the fusion of many smaller cells during development
(e.g., a skeletal muscle cell)
or formed by nuclear division in the absence of cellular division
10.5 and 11.3
Something that works together with another thing to augment the second thing's activity.
For example, a muscle that assists another muscle is said to be a synergist.
An enzyme that helps another enzyme is a synergist.
A lubricating, nourishing fluid found in joint capsules.
The flow of blood from the heart, through the body (not including the lungs), and back to heart.
The period of time during which the ventricles of the heart are contracted.
The pressure measured in the arteries during contraction of the ventricles (during systole).
Regions of the genome where short sequences of nucleotides are repeated one after the other, anywhere from 3-100 times.
A type of lymphocyte.
The major subtypes of T cells are:
•the helper T cells (CD4), secrete chemicals that help killer Ts and B cells proliferate
•the killer T cells (CD8, or cytotoxic T cells), destroy abnormal self-cells (e.g.,cancer cells) or infected cells.
9.4 and 9.7
The cerebral hemispheres.
A specialized region at the ends of eukaryotic chromosomes that contains several repeats of a particular DNA sequence.
These ends are maintained (in some cells) with the help of a special DNA polymerase called telomerase
telomeres slowly degrade with each round of DNA replication;
this is thought to contribute to the eventual death of the cell.
4.1, 4.4 and 6.7
The fourth (and final) phase of mitosis.
the nuclear envelope reforms, chromosomes de-condense, and the mitotic spindle is disassembled.
The fourth phase of meiosis 1.
identical to mitotic telophase, except that the number of chromosomes is now reduced by half.
After this phase the cell is considered to be haploid.
Note however, that the chromosomes are still replicated, and the sister chromatids must still be separated during meiosis 2.
The fourth and final phase of meiosis 2.
identical to mitotic telophase, except that the number of chromosomes was reduced by half during meiosis 1.
Summation by a postsynaptic cell of input (EPSPs or IPSPs) from a single source over time.
Strong bands of connective tissue that connect skeletal muscle to bone.
A genetic cross between an organism displaying a recessive phenotype (homozygous recessive) and an organism displaying a dominant phenotype (for which the genotype is unknown)
done to determine the unknown genotype.
The primary male sex organ.
suspended outside the body cavity in the scrotum and have two functions:
(1) produce sperm
(2) secrete testosterone.
The primary androgen (male sex steroid).
a steroid hormone produced secreted by the interstitial cells of the testes.
It triggers the development of secondary male sex characteristics during puberty (including spermatogenesis) and maintains those characteristics during adulthood.
A smooth sustained muscle contraction, such as occurs in skeletal muscle when stimulation frequency is high enough (this is the normal type of contraction exhibited by skeletal muscle)
A pair of replicated homologous chromosomes.
Tetrads form during prophase 1 of meiosis so that homologous chromosomes can exchange DNA in a process known as "crossing over."
The central structure of the diencephalon of the brain.
acts as a relay station and major integrating area for sensory impulses.
A layer of cells surrounding the granulosa cells of the follicles in an ovary.
help produce the estrogen secreted from the follicle during the first phase of the ovarian cycle.
A receptor that responds to change in temperature.
DNA replication in prokaryotes
named because as replication proceeds around the single, circular chromosome, it takes on the appearance of the Greek letter theta.
In skeletal and cardiac muscle tissue, a filament composed of bundles of myosin molecules.
The myosin head groups attach to the thin filaments during muscle contraction and pull them toward the center of the sarcomere.
In skeletal and cardiac muscle tissue, a filament composed of actin, tropomyosin and troponin.
attached to the Z lines of the sarcomeres and slide over thick filaments during muscle contraction.
A blood clot that forms in an unbroken blood vessel.
Thrombi are dangerous because they can break free and begin traveling in the bloodstream (become an embolus).
Emboli ultimately become stuck in a small vessel and prevent adequate blood delivery to tissues beyond the sticking point, leading to tissue death.
A brain embolism can lead to stroke, a heart embolism to a heart attack, and pulmonary embolism to respiratory failure.
1 of 4 aromatic bases found in DNA.
pyrimidine, and pairs with adenine.
An immune organ located near the heart.
the site of T cell maturation and is larger in children and adolescents.
thyroid stimulating hormone (TSH)
A tropic hormone produced by the anterior pituitary gland that targets the thyroid gland.
stimulating it to produce and release thyroid hormone.
AKA thyroid hormone
produced and secreted by follicle cells in the thyroid gland.
It targets all cells in the body and increases overall body metabolism.
The volume of air inhaled and exhaled in a normal, resting breath
typically about 500 mL.
AKA occluding junctions
form a seal between cells that prevents the movement of substances across the cell layer, except by diffusion through the cell membranes themselves.
found between the epithelial cells forming the capillaries in the brain (the blood-brain barrier).
the unresponsiveness of the immune system to normal proteins
An organism that can survive in the presence of oxygen (oxygen is not toxic), but that does not use oxygen during metabolism (anaerobic metabolism only).
Paired masses of lymphatic tissue near the back of the throat that help trap inhaled or swallowed pathogens.
A tenet of Gestalt psychology where the brain applies experience and expectations to interpret sensory information.
An enzyme that cuts one or both strands of DNA to relieve the excess tension caused by the unwinding of the helix by helicase during replication.
total lung capacity
The maximum volume of air that the lungs can contain.
the sum of the vital capacity and the residual volume
typically about 6000 ml. (6 L)
Having the ability to become anything
e.g, a zygote is totipotent.
The main air tube leading into the respiratory system.
made of alternating rings of cartilage and connective tissue.
10.6 and 12.2
The enzymatic process of reading a strand of DNA to produce a complimentary strand of RNA.
4.3 and 4.7
The transfer by a lysogenic virus of a host cell genome to a new host.
A point mutation in which a pyrimidine is substituted for a pyrimidine, or a purine is substituted for a purine.
The process of reading a strand of mRNA to synthesize protein.
Protein translation takes place on a ribosome.
4.3 and 4.7
The protein of an integral membrane protein that passes through the lipid bilayer.
Segments of the genome that can "jump" from one location to another.
Can lead to mutations depending on the final locations of the transposon.
See "T tubules."
A point mutation in which a pyrimidine is substituted for a purine, or vice versa.
See "atrioventricular valve."
The type of RNA that carries an amino acid from the cytoplasm to the ribosome for incorporation into a growing protein
The attachment of amino acid to a tRNA
(note that this is a specific interaction).
tRNA loading requires two high-energy phosphate bonds.
The outer ring of cells of a blastocyst.
takes part in formation of a placenta.
A hormone that controls the release of another hormone.
A helical protein that winds around actin helices in skeletal and cardiac muscle cells to form the thin filament of the sarcomere.
In the absence of Ca2+, tropomyosin covers the myosin-binding sites on actin and prevents muscle contraction.
When calcium is present, a conformational change in tropomyosin occurs so that the myosin-binding sites are exposed and muscle contraction can occur.
A globular protein that associates with tropomyosin as part of the thin filament of the sarcomere.
Troponin is the protein that binds Ca2+, which causes the conformational change in tropomyosin required to expose the myosin binding sites on actin and initiate muscle contraction.
A set of genes for the enzymes necessary to synthesize tryptophan
under the control of a single promotor, the expression of which is inhibited by the presence of tryptophan (this is a repressible system).
The main protease secreted by the pancreas
activated (from trypsinogen) by enterokinase, and subsequently activates the other pancreatic enzymes.
AKA transverse tubules
deep invaginations of the plasma membrane found in skeletal and cardiac muscle cells.
These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell.
tumor suppressor genes
Genes that produce proteins that are the inherent defense system in cells to prevent the conversion of the cell into a cancer cell.
p53 is a well-known tumor suppressor gene.
AKA the eardrum
The membrane that separates the outer ear from the middle ear.
type 1 fibers
AKA red slow twitch or red oxidative fibers
skeletal muscle cells that contract slowly and are extremely resistant to fatigue.
type 2 A fibers
AKA fast twitch oxidative fibers
skeletal muscle cells that contract quickly and are somewhat resistant to fatigue.
type 2 B fibers
AKA white fast twitch fibers
skeletal muscle cells that contract quickly and fatigue quickly.
The cord that connects the embryo of a developing mammal of the placenta in the uterus of the mother.
contains fetal arteries (carry blood toward the placenta) and veins (carry blood away from the placenta).
The umbilical vessels derive from the allantois, a structure that develops from the embryonic gut.
A carrier protein that transports a single molecule across the plasma membrane.
universal acceptor (recipient)
A person with blood type AB+.
Because this person's red blood cells possess all of the typical blood surface proteins, they will not display an immune reaction if transfused with any of the other blood types.
A person with blood type O-.
Because this person's red blood cells possess none of the typical blood surface proteins they cannot initiate an immune reaction in a recipient.
Towards the 5' end of an RNA transcript (the 5' end of the DNA coding strand).
The promoter and start sites are "upstream."
1 of 4 aromatic bases found in RNA.
pyrimidine, and pairs with adenine.
A waste product of protein breakdown, produced by the liver and released into the bloodstream to be eliminated by the kidney.
9.4 and 10.1
The tubes that carry urine from the kidneys to the bladder.
The tube that carries urine from the bladder to the outside of the body.
In males it also carries semen and sperm during ejaculation.
The valve that controls the release of urine from the bladder.
It has an internal part made of smooth muscle (thus involuntary) and an external part made of skeletal muscle (thus voluntary)
The shedding of the old endometrium and preparation of a new endometrium for potential pregnancy.
AKA fallopian tubes
extend laterally from either side of the uterus and serve as a passageway for the oocyte to travel from the ovary to the uterus.
This is also the normal site of fertilization.
Severing of the uterine tubes (tubal ligation) results in sterility of the female.
The muscular female organ in which a baby develops during pregnancy.
The deliberate exposure of a person to an antigen in order to provoke the primary immune response and memory cell production.
Typically the antigens are those normally associated with pathogens
thus if the live pathogen is encountered in the future, the secondary immune response can be initiated preventing infection and symptoms.
The constant inhibition provided to the heart by the vagus nerve.
reduces the intrinsic firing rate of the SA node from 120 beats/minute to around 80 beats/minute.
The birth canal
the stretchy, muscular passageway through which a baby exists the uterus during childbirth.
Cranial nerve pair X.
very large mixed nerves (they carry both sensory input and motor output) that innervate virtually every visceral organ.
They are especially important in transmitting parasympathetic input to the heart and digestive smooth muscle.
van't Hoff factor
The van't Hoff factor (or ionizability factor, i) tells us how many ions one unit of a substance will produce in a solution.
For example, glucose is non-ionic (does not dissociate) so i = 1
however NaC1 dissociates into Na+ and C1-, therefore i = 2
The capillaries that surround the tubules of the nephron.
reclaims reabsorbed substance, such as water and sodium ions.
See "ductus deferens."
A blood vessel that carries blood toward the heart chambers.
•do not have muscular walls
•have valves to ensure that blood flows in one direction only
•are typically low-pressure vessels.
One of two large vessels (superior and inferior) that return deoxygenated blood to the right atrium of the heart.
The amount of blood returned to the heart by the vena cavae
One of two large chambers in the heart.
receive blood from the atria and pump it out of the heart.
The right ventricle has thin walls and pumps deoxygenated blood to the lungs through the pulmonary artery.
The left ventricle has thick walls and pumps oxygenated blood to the body through the aorta.
Paired glands near the posterior of the vaginal opening that secrete an alkaline mucus upon sexual arousal.
The mucus helps to reduce the acidity of the vagina (which could be harmful to sperm) and lubricates the vagina to facilitate penetration.
Folds of the intestinal mucosa that project into the lumen of the intestine
serve to increase the surface area of the intestine for absorption.
Short pieces of circular single-stranded RNA that do not code for protein but interfere with normal gene expression.
Mostly they cause diseases in plants
the only human disease linked to viroids is hepatitis D.
A non living intracellular parasite.
typically just pieces of nucleic acid surrounded by a protein coat.
The maximum amount of air that can be forcibly exhaled from the lungs after filling them to their maximum level
typically about 4500 ml
One of several different nutrients that must be consumed in the diet, and generally not synthesized in the body.
Vitamins can be hydrophobic (fat-soluble) or hydrophilic (water soluble)
A thick, gelatinous fluid found in the posterior segment of the eye (between the lens and the retina).
only produced during fetal development and helps maintain intra-ocular pressure (the pressure inside the eyeball)
voltage-gated ion channel
An ion channel that is opened or closed based on the electrical potential across the plasma membrane.
Once opened, the channel allows ions to cross the membrane according to their concentration gradients.
Examples are the Na+ and K+ voltage-gated channels involved in the action potential of neurons.
states that two stimuli must differ by a constant proportion in order for their difference to be perceptible.
Early embryonic ducts that can develop into male internal genitalia under the proper stimulation (testosterone).
The silencing of one of the two X chromosomes in female cells, so that only one is active.
An embryonic structure particularly important in egg-laying animals because it contains the yolk, the only source of nutrients for the embryo developing inside the egg.
In humans, the yolk sac is very small (since mammals get their nutrients via the placenta) and is the site of synthesis of the first red blood cells.
The ends of a sarcomere.
A thick, transparent coating rich in glycoproteins that surrounds an oocyte.
A diploid cell formed by the fusion of two gametes during sexual reproduction.
An inactive precursor of an enzyme, activated by various methods
(acid hydrolysis, cleavage by another enzyme, etc.)
4.9 and 10.6
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