762 terms

AP Biology Study Set for the 2012 Curriculum

STUDY
PLAY
metabolic pathway
Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.
catabolic pathways
Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.
anabolic pathways
Metabolic pathways that consume energy to build complicated molecules from simpler ones.
bioenergenetics
The study of how organisms manage their energy resources.
free energy
Measures the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
endergonic reaction
Reaction that absorbs free energy from its surroundings.
exergonic reaction
Reaction that proceeds with a net release of free energy.
energy coupling
The use of an exergonic process to drive an endergonic one.
catalyst
A chemical agent that speeds up a reaction without being consumed by the reaction.
enzyme
A catalytic protein.
activation energy
The amount of energy needed to push the reactants over an energy barrier.
enzyme-substrate complex
When an enzyme binds to its substrate, it forms:
active site
A pocket or groove on the surface of the enzyme.
cofactor
Non-protein helpers that may be bound tightly to the enzyme as a permanent resident, or may bind loosely and reversibly along with the substrate.
coenzyme
If the cofactor is an organic molecule.
competitive inhibitors
Reduce the productivity of enzymes by blocking substrates from entering active sites.
noncompetitive inhibitors
Impede enzymatic reactions by binding to another part of the enzyme (other than the active site).
allosteric regulation
When a protein's function at one site is affected by the binding of a regulatory molecule to a separate site.
feedback inhibition
A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.
keystone species
A plant or animal that plays a unique and crucial role in the way an ecosystem functions.
gene duplication
The generation of extra copies of a gene in a genome over evolutionary time. A mechanism by which genomes can acquire new functions.
temperature-dependent sex determination (TDSD)
In some reptiles, when the temperature during a critical period of embryonic development determines the gender of the offspring.
mutation
A change of the nucleotide sequence of the genome.
heterozygote advantage
Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools.
point mutation
A mutation that affects a single nucleotide, usually by substituting one nucleotide for another.
frameshift mutation
Mutation that shifts the "reading frame" of the genetic message by the insertion or deletion of a nucleotide.
horizontal gene transfer
The transfer of genes between organisms in a manner other than traditional reproduction.
bacterial conjugation
The transfer of plasmids between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells.
transformation
The genetic alteration of a cell resulting from the direct uptake, incorporation and expression of exogenous genetic material from its surroundings and taken up through the cell membrane.
transduction
The process by which DNA is transferred from one bacterium to another by a virus.
bacteriophage
A virus that infects and replicates within bacteria.
virus
A virus is a small infectious agent that replicates only inside the living cells of other organisms.
latent viral infection
The ability of a pathogenic virus to lie dormant within a cell during the lysogenic part of the viral life cycle.
lytic cycle
Viral life cycle in which the viral DNA exists as a separate molecule within the bacterial cell. Results in the destruction of the infected cell.
lysogenic cycle
Viral life cycle characterized by integration of the viral nucleic acid into the host bacterium's genome. The viral genetic material can be transmitted to daughter cells.
Hersey-Chase Experiment
Devised an experiment that showed that only the DNA of T2 phages enters a bacterial cell during infection.
Frederick Griffith
This person discovered transformation during an experiment that involved injecting mice with smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells.
Erwin Chargaff
Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine.
Avery, MacLeod, McCarty
Determined that DNA was Griffith's "Transforming Factor."
Rosalind Franklin
Used X-ray diffraction to discover the double-helical structure of DNA.
Watson and Crick
Developed the double helix model of DNA.
one gene-one polypeptide hypothesis
The premise that a gene is a segment of DNA that codes for one polypeptide.
DNA
A long, linear polymer found in the nucleus of a cell formed from nucleotides and shaped like a double helix.
nucleic acid
An organic compound, either RNA or DNA, whose molecules are made up of one or two chains of nucleotides and carry genetic information.
nucleotide
Monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base.
purines
Nitrogenous bases that have a double ring structure.
pyrimidines
Nitrogenous bases that have a single ring structure.
antiparallel
The opposite arrangement of the sugar-phosphate backbones in a DNA double helix.
phosphodiester bond
Strong covalent bond linking the carbon-3 atom a deoxyribose sugar in one nucleotide to the phosphate group of another nucleotide.
replication
The process whereby DNA makes a copy of itself prior to cell division.
semiconservative model
Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand.
origins of replication (ORI)
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
DNA polymerase
An enzyme that catalyzes the formation of the DNA molecule.
transcription
Synthesis of an RNA molecule from a DNA template.
replication fork
A Y-shaped region on a replicating DNA molecule where new strands are growing.
lagging strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.
leading strand
The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.
primase
An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
messenger RNA (mRNA)
Carries genetic message from the DNA to he protein-synthesizing machinery of the cell.
Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
DNA helicase
An enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.
topoisomerase
A protein that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.
single-strand binding proteins
Bind to and stabilizes single-stranded DNA until it can be used as a template.
telomeres
Repeated DNA sequences at the ends of eukaryotic chromosomes.
telomerase
An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.
translation
The synthesis of a polypeptide, which occurs under the direction of mRNA.
RNA processing
The modification of mRNA before it leaves the nucleus that is unique to eukaryotes.
primary transcript
The initial mRNA transcript that is transcribed from a protein coding gene. Also called pre-mRNA.
template strand
The DNA strand that provides the template for ordering the sequence of nucleotides in an mRNA transcript.
codons
mRNA base triplets.
reading frame
Reading mRNA nucleotides in the correct groupings.
RNA polymerase
Enzyme that links together the growing chain of ribonucleotides during transcription.
promoter
A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing mRNA.
terminator
In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene.
transcription factors
Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.
transcription initiation complex
The assembly of transcription factors and RNA polymerase.
TATA box
Ccrucial promoter DNA sequence.
5 ' cap
The 5 ' end of a pre-mRNA molecule modified by the addition of a cap of guanine nucleotide.
poly-A tail
Modified end of the 3 ' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides.
RNA splicing
Process by which the introns are removed from RNA transcripts and the remaining exons are joined together.
introns
Noncoding segments of nucleic acid that lie between coding sequences.
exons
Coding segments of eukaryotic DNA.
pre-mRNA
The precusor strand of mRNA produced by gene transcription that contains both introns and exons.
splicosome
Different particles that recognize splice sites are compiled in a large assembly. A complex of RNA and protein subunits. Removes introns from a transcribed pre-RNA segments.
ribozymes
RNA molecules that function as enzymes.
alternative RNA splicing
Genes giving rise to two or more different polypeptides depending upon which segments are treated as exons.
activator
Proteins that bind to the enhancer region, which is very far upstream from the promoter region, to initiation transcription.
regulator
protein that can bind just upstream from the promoter, activating the transcription initiation complex.
domains
Discrete structural and functional regions of proteins.
transfer RNA (tRNA)
Interpreter of a series of codons along a mRNA molecule.
Central Dogma of Molecular Biology
DNA to RNA to protein.
anticodon
Specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
wobble
Flexibility in the base-pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position of a codon.
ribosomal RNA (rRNA)
RNA molecules that construct ribosomal subunits.
ribosomal P site
Site that holds tRNA carrying the growing polypeptide chain.
ribosomal A site
Site that holds the tRNA carrying the next amino acid to be added to the chain.
ribosomal E site
Site where discharged tRNAs leave the ribosome.
polyribosomes
Strings of ribosomes that work together to translate a RNA message.
transformation
A change in genotype and phenotype due to the assimilation of external DNA by a cell.
gene expression
Conversion of the information encoded in a gene first into messenger RNA and then to a protein.
micro-RNA (miRNA)
Small single stranded RNA molecules that bind to mRNA and can degrade mRNA or block its translation.
siRNAs (small interfering RNAs)
RNAs of similar size and functions as miRNAs that inhibit gene expression
RNA interference (RNAi)
Blocking gene expression by means of a miRNA silencing complex
recombinant DNA
A DNA molecule made in vitro with segments from different sources.
biotechnology
The manipulation of living organisms or their components to produce useful products.
gene cloning
The production of multiple copies of a gene.
restriction enzyme
A degradative enzyme that recognizes and cuts up DNA (including that of certain phages) that is foreign to a bacterium.
restriction site
A specific sequence on a DNA strand that is recognized as a cut siteby a restriction enzyme.
restriction fragment
The fragment of DNA that is produced by cleaving DNA with a restriction enzyme.
sticky end
A single-stranded end of a double-stranded DNA restriction fragment.
DNA ligase
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.
cloning vector
DNA molecules that can carry foreign DNA into a host cell and replicate there.
denaturation
In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix.
polymerase chain reaction (PCR)
A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides.
gel electrophoresis
The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.
restriction fragment length polymorphisms (RFLPs)
Differences in the restriction sites on homologous chromosomes that result in different restriction fragment patterns.
Human Genome Project
An international collaborative effort to map and sequence the DNA of the entire human genome.
genetic engineering
The direct manipulation of genes for practical purposes.
plasmid
Small extra-chromosomal, double-stranded circular DNA molecules.
RNA primer
Short segment of RNA used to initiate synthesis of a new strand of DNA during replication.
retrovirus
Virus that contains RNA as its genetic information.
reverse transcriptase
A polymerase that catalyzes the formation of DNA using RNA as a template.
natural selection
A population can change over time if individuals with more fit traits leave more offspring than less fit individuals.
evolutionary adaptation
An accumulation of inherited characteristics that enhance organisms' ability to survive and reproduce in specific environments.
artificial selection
Humans modifying species for desired traits through selective breeding.
decent with modification
Darwin's way of referring to evolution.
MRSA
Methicillin-resistant Staphylococcus aureus.
fitness
Individuals whose inherited traits confer an advantage have a better chance of surviving in a given environment and will leave more offspring.
homology
Similarity resulting from common ancestry.
homologous structures
Same structure, different function. Comes from common ancestor.
comparative embryology
Embryos of vertebrates share many anatomical homologies.
vestigial structures
Are little or no importance to organism, but remain from an ancestor.
biogeography
Geographic distribution of species.
population
Group of individuals of the same species living in the same area.
population genetics
Study of allele frequency distribution and change under the influence of evolutionary processes.
gene pool
All the genes in a given population at a given time.
allele frequency
Proportion of an allele in a gene pool.
Hardy-Weinberg Theorem
Helps measure changes in allele frequencies over time . Provides an "ideal" population to use as a basis of comparison.
mutation
Changes in nucleotide sequence in DNA.
sexual recombination
Crossing over, shuffling of genes during meiosis.
genetic drift
Change in allele frequencies due to chance, not natural selection.
bottleneck effect
When a population has been dramatically reduced, and the gene pool is no longer reflective of the original population's.
founder effect
When a small number of individuals colonize a new area; new gene pool not reflective of original population.
gene flow
When a population gains or loses alleles., movement of alleles into or out of a population due to the migration of individuals to or from the population.
genetic variation
Heritable variations in a population.
quantitative characteristics
Characteristics that vary along a continuum, usually due to influence of two or more genes.
heterozygous advantage
Maintains recessive alleles in a population.
sexual selection
Natural selection for mating success.
microevolution
Change in genetic makeup of a population from generation to generation.
macroevolution
Evolutionary change above the species level.
directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes.
disruptive selection
Natural selection that favors individuals with either extreme of a trait and may lead to speciation.
geographic variation
Differences between the gene pools of separate populations or population subgroups.
cline
A graded change in a character along a geographic axis.
phylogeny
Evolutionary history of a species or group of species.
systematics
Analytical approach to understanding the diversity and relationships of present and past organisms.
analogy
A similarity due to convergent evolution.
homoplasies
Analogous structures that have evolved independently.
taxonomy
Ordered division of organisms into categories.
bionomial nomenclature
Scientific name.
genus
First part of scientific name.
specific epithet
Second part of scientific name.
phylogenetic trees
Branching diagrams that depict hypotheses about evolutionary relationships.
cladogram
Shows patterns of shared characteristics.
clade
Group of species that includes an ancestral species and all of its descendants.
cladistics
Analysis of how species grouped into clades.
monophyletic group
Ancestral species and all of its descendants.
paraphyletic group
When we lack information about some members of the clade.
polyphyletic group
Several species that lack a common ancestor ( more work is needed to uncover species that tie them together into a monophyletic clade).
shared primitive character
Trait shared beyond the taxon.
shared derived character
Evolutionary novelty unique to that clade.
outgroups
Species or group of species closely related to the ingroup.
phylograms
Length of a branch reflects number of changes in a DNA sequence.
ultrametric trees
Length of branch reflects amounts of time.
maximum parsimony
"Occam's Razor" : first investigate the simplest explanation that is consistent with the facts.
maximum likelihood
Given certain rules of how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events.
the three-domain system
Domains Bacteria, Archae, and Eukarya.
Central Dogma
States that information flows in one direction from DNA to RNA to proteins.
speciation
Origin of new species and the source of biological diversity.
biological species concept
Species is a group of populations whose members have the potential to produce fertile offspring.
reproductive isolation
Barriers that impede members of two different species from producing fertile offspring.
prezygotic barriers
Impede mating or hinder fertilization.
habitat isolation
When two species encounter each other rarely.
temporal isolation
When two species breed at different times of day, season, or years.
behavioral isolation
Incompatible courtship rituals, pheromones, bird songs.
mechanical isolation
Morphological differences prevent fertilization.
gametic isolation
When sperm can't fertilize eggs.
postzygotic barriers
Prevent the hybrid zygote from becoming a fertile adult.
reduced hybrid viability
When the genes of different species interact and impair hybrid development.
reduced hybrid fertility
Sterile hybrids due to uneven chromosome number.
hybrid breakdown
Hybrid is fertile, but when they breed next generation sterile.
allopatric speciation
When a population is divided; leads to speciation.
sympatric speciation
speciation without a divided population.
polyploidy
In plants, the result of extra set of chromosomes during cell division.
autopolyploid
Having more than two sets of chromosomes from a single species.
adaptive radiation
Evolution of many new species from a common ancestor as a result of introduction to new environments.
punctuated equilibrium
New species change most as it buds from a parent species and then changes little for the rest of its existence.
gradualism
A model of evolution in which gradual change over a long period of time leads to biological diversity.
heterochrony
Change in the rate or timing of a developmental event ; an organism's shape depends on relative growth rate of body parts.
allometric growth
Proportioning that gives a body a specific form.
homeotic genes
Determine basic features of where a body part is.
Hox genes
Class of homeotic genes. Changes in these genes can have profound impact on morphology.
metabolic pathway
Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.
catabolic pathways
Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.
anabolic pathways
Metabolic pathways that consume energy to build complicated molecules from simpler ones.
thermal energy
Kinetic energy associated with the random movement of molecules or atoms.
potential energy
Occurs when an object is not moving, but may still posses energy.
first law of thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed
entropy
A measure of disorder or randomness.
second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe.
Gibbs free energy
Measures the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
endergonic reaction
Reaction that absorbs free energy from its surroundings.
exergonic reaction
Reaction that proceeds with a net release of free energy.
energy coupling
The use of an exergonic process to drive an endergonic one.
ATP (adenosine triphosphate)
Composed of a sugar ribose, nitrogenous base adenine, and a chain of three phosphate groups bonded to it.
phosphorylation
The metabolic process of introducing a phosphate group into an organic molecule.
bioenergetics
Flow of energy through an animal. Limits its behavior, growth, reproduction.
metabolic rate
Amount of energy an animal uses in a unit of time, and the sum of all the energy-requiring biochemical reactions.
endothermic
Animals that are warmed mostly by heat generated by metabolism.
ectothermic
Animals that gain heat mostly from external sources.
homeostasis
"Steady state" or "constant internal milieu".
regulator
An animal that uses internal control mechanisms to moderate internal change in the face of external fluctuation.
conformer
An animal that allows its internal condition to vary with certain external changes.
heterotroph
Organism that obtains energy from the foods it consumes.
chemosynthesis
Process by which some organisms, such as certain bacteria, use chemical energy to produce carbohydrates.
autotroph
Organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds.
photoautotrophs
Organisms that use light as a source of energy to synthesize organic substances.
chlorophyll
Green pigment located within the chloroplasts.
stomata
Microscopic pores in the leaf which lets carbon dioxide in and oxygen out. Also where water is lost.
grana
Stack of thylakoids.
stroma
Fluid inside the chloroplast where the Calvin Cycle happens.
thylakoid
Flattened membranes in the chloroplast where the light reactions take place.
photosynthesis equation
light reactions
Part of photosynthesis that involves light. ATP and NADPH are produced. Takes place on the thylakoid membrane.
pigments
Molecules that absorb, reflect, or transmit light.
photosystem
A cluster of pigments embedded into a thylakoid membrane.
photolysis
In the thylakoid membranes of a chloroplast during light-dependant reactions, two molecules of water are split to form oxygen, hydrogen ions, and electrons.
phosphoralation
Process of adding a phosphate group.
carbon fixation
The initial incorporation of carbon into organic compounds.
Calvin cycle
Carbon fixation process in photosynthesis. Forms sugar and other organic compounds.
absorption spectrum
A graph plotting a pigment light light absorption.
action spectrum
A profile of the relative performance of the different wavelengths in photosynthesis.
chlorophyll a
The only pigment that can participate directly in the light reactions.
carotenoids
Accessory pigments that broaden the spectrum of colors that can drive photosynthesis.
P680
The reaction center chlorophyll in the photosystem II.
P700
The reaction center cholophyll in the photosystem I.
reaction center
The location of the first light driven chemical reaction of photosynthesis.
primary electron acceptor
Specialized molecule that traps a high energy electron before it can return to ground state in the chlorophyll.
chemiosmosis
Process by which protons are pumped into the thylakoid membrane. Protons passively flow through the ATP synthase, which leads to the synthesis of ATP.
rubisco
The most abundant protein on earth. Performs Carbon Fixation in the Calvin Cycle.
fermentation
A partial degradation of sugars that occur without the use of oxygen.
cellular respiration
When oxygen is consumed as a reactant along with the organic fuel.
electron transport chain
Breaks the fall of electrons to oxygen in several energy-releasing steps.
glycolosis
Breaking glucose into two molecules of a compound called pyruvate.
Krebs cycle
Completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide.
oxidative phosphorylation
When energy is released at each step of the chain is stored in a form the mitochondrion can use to make ATP.
substrate-level phosphorylation
When an enzyme transfers a phosphate group from a substrate molecule.
acetyl-CoA
Is formed when pyruvate first enters into the mitochondria via active transport.
ATP synthase
The enzyme that make ATP from ADPand inorganic phosphate.
chemiosmosis
When energy is stored in the form of a hydrogen ion gradient across a membrane which is used to drive cellular work.
proton-motive force
Emphasizes the capactiy of the gradient to preform work.
anaerobic
Occurs by fermentation, which generate ATP solely by substrate-level phosphorylation.
alcohol fermentation
When pyruvate is converted to ethanol in 2 steps.
lactic acid fermetation
When pyruvate is reduced directly by NADH to form lactic as am end product, with no release of carbon dioxide.
facultative anaerobes
Bacteria that can make enough ATP to survive using fermentation or respiration.
Greenhouse Effect
Carbon dioxide and water vapor in atmosphere trap infrared radiation, re-reflecting it back toward earth.
nutrient cycling
The circulation of chemicals necessary for life, from the environment, through organisms, and back to the environment.
eutrophication
Sewage and fertilizer runoff adds nutrients to lakes; phytoplankton decreases and cyanobacteria increases.
critical load
The amount of added nutrient that can be absorbed by plants without damaging ecosystem.
polar
Molecule with partial charges. Mixes with water.
nonpolar
No partial charges. Do not mix with water.
electronegativity
Attraction of an atom for electrons in a covalent bond.
cohesion
Water molecules sticking to each other.
adhesion
Water molecules sticking to other surfaces.
solute
Something dissolved in a solution.
solvent
Dissolving agent of a solution.
specific heat
The heat required to raise the temperature of one gram of a substance one degree centigrade.
heat of vaporization
The heat absorbed by a unit mass of a material at its boiling point in order to convert the material into a gas at the same temperature.
heat of fusion
The heat absorbed by a unit mass of a solid at its melting point in order to convert the solid into a liquid at the same temperature.
evaporative cooling
The property of a liquid whereby the surface becomes cooler during evaporation, owing to a loss of highly kinetic molecules to the gaseous state.
aqueous solution
a solution in which water is the solvent
plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition.
diffusion
When a substance moves from an area of higher concentration to an area of lower concentration. Due to entropy.
osmosis
The diffusion of water through a selectively permeable membrane.
dialysis
The diffusion of small solutes through a selectively permeable membrane.
passive transport
Transport of a substance across a cell membrane by diffusion. Going with a concentration gradient.
active transport
When a cell gets materials or excretes them by using its own energy, usually through ATP; going against a concentration gradient.
hypertonic
Describes a solution that has a greater concentration of total solute.
hypotonic
Describes a solution that has a lesser concentration of total solute.
isotonic
Describes solutions that have an equal concentration of total solutes.
turgor pressure
The pressure inside of a cell as a cell pushes itself against the cell wall.
plasmolysis
This happens when a cell shrinks inside its cell wall while the cell wall remains intact.
flaccid
This happens when water moves, but the amount within the cell is constant; no pressure builds.
turgid
A cell with a cell wall that has a reasonable amount of pressure but is healthy.
cytolysis
This happens when a cell swells until pressure bursts it, resulting in cell death.
crenation
This happens when a cell shrinks and shrivels; can result in cell death if severe.
water potential
The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.
solute potential
This measurement has a maximum value of 0; it decreases as the concentration of a solute increases.
pressure potential
This measurement has a minimum value of 0 (when the solution is open to the environment); it increases as pressure increases.
selective permeability
A property of a plasma membrane that allows some substances to cross more easily than others.
amphipathic
Molecules are said to be this when it has regions that are both hydrophilic and hydrophobic.
fluid mosaic model
Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.
integral proteins
Transmembrane proteins with hydrophobic regions that completely span the hydrophobic interior of the membrane.
transmembrane proteins
Integral proteins that span the membrane.
peripheral proteins
The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.
transport
An exchange of molecules (and their kinetic energy and momentum) across the boundary between adjacent layers of a fluid or across cell membranes.
enzymatic activity
A protein built into the membrane with active site exposed.
cell-cell recognition
The function of membrane proteins in which some glycoproteins serve as ID tags that are recognized by membrane proteins of other cells.
glycolipids
Membrane carbohydrates that are covalently bonded to lipids.
glycoproteins
Membrane carbohydrates that are covalently bonded to proteins.
transport protein
A membrane protein that is responsible for moving hydrophilic substances from one side to the other.
channel protein
A membrane protein, specifically a transport protein, that has a hydrophilic channel that certain molecules or atomic ions use as a tunnel.
aquaporin
A membrane protein, specifically a transport protein, that facilitates the passage of water through channel proteins.
carrier protein
A membrane protein, specifically a transport protein, that holds onto molecules and changes their shapes in a way that shuttles them across the membrane.
concentration gradient
A difference in the concentration of a substance across a distance.
tonicity
The ability of a solution to cause a cell to gain or lose water; depends partly on concentration of nonpenetrating solutes relative to inside of cell.
osmoregulation
The control of water balance.
facilitated diffusion
Passive diffusion that is aided by transport proteins, but that does not require cellular energy.
membrane potential
The voltage of a plasma membrane.
electrochemical gradient
The combination of forces that acts on membrane potential.
gated channel
A protein channel in a cell membrane that opens or closes in response to a particular stimulus.
proton pump
An electrogenic pump that works largely with H+ ions.
cotransport
The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.
exocytosis
Occurs when a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane.
endocytosis
Occurs when a cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane.
phagocytosis
Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
pinocytosis
A type of endocytosis in which the cell "gulps" droplets of fluid into tiny vesicles.
nuclear envelope
Double membrane perforated with pores that control the flow of materials in and out of the nucleus.
nuclear lamina
A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.
endomembrane system
A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.
vesicle
Small membrane-bound sac that functions in moving products into, out of, and within a cell.
smooth ER
Synthesis of lipids, phospholipids and steroid sex hormones, and helps detoxify drugs and toxins.
rough ER
A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins.
glycoprotein
A protein with one or more carbohydrates covalently attached to it.
transport vesicles
Vesicles in transit from one part of the cell to another.
Golgi apparatus
Stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum.
lysosome
A cell organelle that contains digestive enzymes.
contractile vacuoles
A membranous sac that helps move excess water out of the cell.
peroxisome
A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide.
cell wall
Strong layer around the cell membrane in plants, algae, and some bacteria.
homeostasis
"Steady state" or "constant internal milieu".
negative feedback
A type of regulation that responds to a change in conditions by initiating responses that will counteract the change. Maintains a steady state.
positive feedback
A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state.
thermoregulation
Process of maintaining an internal temperature within a tolerable range.
vasodialation
Increases in the diameter of superficial blood vessels; cools the body.
vasoconstriction
Reduces blood flow and heat transfer by decreasing the diameter of superficial blood vessels.
ethylene
Plant hormone that promotes leaf abscission and fruit ripening.
type 1 diabetes mellitus
Diabetes in which no beta-cell production of insulin occurs and the patient is dependent on insulin for survival.
type 2 diabetes mellitus
Diabetes in which the body produces insulin, but not enough, or there is insulin resistance. The patient usually is not dependent on insulin for survival.
circadian rhythms
A physiological cycle of about 24 hours that is present in all eukaryotic organisms and that persists even in the absence of external cues.
photoperiodism
A physiological response to photoperiod, the relative lengths of night and day. An example of photoperiodism is flowering.
phytochrome
A class of light receptors in plants. Mostly absorbing red light, these photoreceptors regulate many plant responses, including seed germination and shade avoidance.
critical night length
The number of hours of darkness that determines whether or not a plant will flower.
long-day plants
A plant that flowers only when the light period is longer than a critical length. Usually spring or early summer.
short-day plants
A plant that flowers only when the light period is shorter than a critical length. Usually fall or winter.
day-neutral plants
A plant whose flowering is not affected by photoperiod.
phototropism
Growth of a plant shoot toward or away from light.
auxin
Indoleacetic acid (IAA), a natural plant hormone that has a variety of effects, including cell elongation, root formation, secondary growth, and fruit growth.
torpor
Physiological state in which activity is low and metabolism decreases.
hibernation
long-term torpor that is an adaptation to winter cold and food scarcity
estivation
Summer torpor. Enables animals to survive long periods of high temperatures and scarce water supplies.
daily torpor
In small mammals and birds, daily lowering of metabolism that allows them to survive on stored energy.
migration
Relatively long-distance movement of individuals, usually on a seasonal basis.
kinesis
A simple change in activity or turning rate in response to a stimuli.
taxis
Automatic, oriented movement toward or away from some stimuli.
chemotaxis
The phenomenon whereby somatic cells, bacteria, and other organisms direct their movements according to certain chemicals in their environment.
innate immunity
Immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens.
acquired immunity
Immunity that is present only after exposure and is highly specific.
lymphocytes
White blood cells.
antibodies
Protein that is produced by lymphocytes and that attaches to a specific antigen.
neutrophils
The most abundant type of white blood cell. Phagocytic and tend to self-destruct as they destroy foreign invaders, limiting their life span to a few days.
complement system
A group of about 30 blood proteins that may amplify the inflammatory response, enhance phagocytosis, or directly lyse extracellular pathogens.
interferon
Protein produced by cells in response to being infected by a virus; helps other cells resist the virus.
inflammtory response
Innate response with the purpose of containing a site of damage, localizing the response, eliminating the invader and restore tissue function.
histamine
Chemical stored in mast cells that triggers dilation and increased permeability of capillaries.
natural killer (NK) cells
These cells kill cancer cells and cells infected with viruses. They bind to their targets and deliver a lethal burst of chemicals to produce holes in the target cell's membrane leading to its destruction.
antigen
Any foreign molecule that is specifically recognized by lymphocytes and elicits an immune response.
epitope
Small, accessible portion of an antigen that can be recognized.
B lymphocytes (B cells)
Lymphocyte that matures in the bone marrow and secretes antibodies.
T lymphocytes (T cells)
Lymphocyte that matures in the thymus and acts directly against antigens in cell-mediated immune responses.
immunoglobulins
Secreted antibodies.
antigen presentation
The process by which an MHC molecule binds to a fragment of an intracellular protein antigen and carries it to the cell surface, where it is displayed and can be recognized by a T cell.
thymus
Gland in the thoracic cavity above the heart where T lymphocytes mature.
memory cells
General term for lymphocytes that are responsible for immunological memory and protective immunity.
primary immune response
Immune response the first time the body is exposed to a particular antigen. Does not peak until 10-17 days after exposure.
secondary immune response
Immune response after the body has already been exposed to a specific antigen. Response is faster, of greater magnitude, and more prolonged.
humoral immune response
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies.
cell-mediated immune response
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells.
helper T cells
Activate macrophages, B cells and T cells.
active immunity
A form of acquired immunity in which the body produces its own antibodies against disease-causing antigens.
passive immunity
Immunity conferred by transferring antibodies from an individual who is immune to a pathogen to another individual.
B cell receptor
The antigen receptor on B cells: a Y-Shaped, membrane-bound molecule consisting of two identical heavy chains and two identical light chains.
T cell receptor
Antigen receptors on a T cell. Unlike antibodies, T cell receptors are never produced in a secreted form.
Major histocompatibility compex (MHC)
Binds to a fragment of an antigen within a cell and presents it on the surface of the membrane.
cytotoxic T cells or "killer T cells"
T cells that directly attack infecting organisms; these cells attack antigen labeled foreign or host tissue.
biotic factors
The living parts of an ecosystem.
abiotic factors
The nonliving parts of an ecosystem.
density-dependent inhibition
The phenomenon observed in normal animal cells that causes them to stop dividing when they come into contact with one another.
biofilm
A surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation.
symbiosis
A close and often long-term interaction between two or more different species.
mutualism
Symbiotic relationship in which both species benefit from the relationship.
commensalism
Symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed.
parasitism
Symbiotic relationship in which one organism lives in or on another organism, called the host, and consequently harms it.
endoparasites
Parasites that live within the body of their host.
ectoparasites
Parasites that feed on the external surface of a host.
parasitoidism
A type of parasitism in which an insect lays eggs on or in a living host; the larvae then feed on the body of the host, eventually killing it.
disease
An abnormal condition that affects the body of an organism.
pathogen
An organism that causes disease.
epidemic
A widespread outbreak of an infectious disease.
predation
An interaction in which one organism kills another for food.
predator
Any animal that lives by preying on other animals.
prey
An animal hunted or caught for food.
cryptic coloration
Camouflage that makes a predator or prey difficult to spot.
aposematic coloration
The bright coloration of animals with effective physical or chemical defenses that acts as a warning to predators.
Batesian mimicry
A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators.
Müllerian mimicry
A type of mimicry in which two or more unpalatable species resemble each other.
population density
Number of individuals per unit area.
food web
Network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem.
algal bloom
An immediate increase in the amount of algae and other producers that results from a large input of a limiting nutrient.
stomata
A pore found in the epidermis of leaves, stems and other organs that is used to control gas exchange.
food vacuole
A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell.
gastrovascular cavity
A single opening that takes in nutrients and exchanges gases with the environment.
tracheal system
In insects, a system of branched, air-filled tubes that extends throughout the body and carries oxygen directly to cells.
spiracles
In insects, openings on the abdomen and thorax through which air enters and waste gases leave the body.
tracheoles
In insects, narrow tubes branching from trachea and making direct contact with cells to facilitate gas exchange.
trachea
Membranous tube with cartilaginous rings that conveys inhaled air from the larynx to the bronchi.
bronchi
Two short branches located at the lower end of the trachea that carry air into the lungs.
bronchioles
Small passageways by which the air passes from the bronchi to the air sacs of the lungs.
alveoli
Tiny sacs of lung tissue specialized for the exchange of gases between air and blood.
positive pressure breathing
A breathing system used by amphibians in which air is forced into the lungs.
negative pressure breathing
A breathing system in which air is pulled into the lungs when the lung volume is expanded.
protonephridia
An excretory system, such as the flame bulb system of flatworms, consisting of a network of tubules lacking internal openings.
flame cells
In flatworms, specialized cells that remove excess water from the body.
metanephridia
In annelid worms, a type of excretory tubule with internal openings that collect body fluids and external openings that excrete waste from the body.
kidney
Organ in vertebrates that removes urea, excess water, and other waste products from the blood and passes them to the ureter.
nephron
The functional unit of the kidney.
evapotranspiration
Combination of evaporation and transpiration.
biological magnification
The increasing concentration of a harmful substance in organisms at higher trophic levels in a food chain.
DDT
An insecticide that is also toxic to animals and humans.
indigenous
Native to a certain area.
invasive species
Species introduced to new areas that often disrupt the indigenous communities.
fracking
Slang for hydraulic fracturing- a process that removes natural gas from shale.
habitat fragmentation
Breakup of a habitat into smaller pieces, usually as a result of human activities.
macrophage
A phagocytic cell present in many tissues that functions in both specific and nonspecific immunity.
hemocyte
Immune cells that circulate within the hemolymph of insects and ingest foreign substances by phagocytosis.
hemolymph
In insects, combined blood and lymph.
pattern-recognition receptors (PRRs)
Proteins expressed by cells of the innate immune system that evolved before adaptive immunity.
microorganism associated molecular patterns (MAMPs)
Molecules associated with groups of pathogens that are recognized by cells of the innate immune system.
systemic acquired resistance (SAR)
A "whole-plant" resistance response that occurs following an earlier localized exposure to a pathogen.
determination
The point during development at which a cell becomes committed to a particular fate due to cytoplasmic effects or to induction by neighboring cells.
cell differentiation
The process by which a cell becomes specialized for a specific structure or function.
zygote
Diploid cell resulting from the union of a haploid egg and a haploid sperm.
genomic equivalence
All cells in an organism contain the same complement of genes. These are the same set of genes that are established in the fertilized egg.
totipotent
Cells that are able to develop into any type of cell found in the body.
pluripotent
Able to give rise to multiple, but not all, cell types.
cloning
Making a genetically identical copy of DNA or of an organism.
nuclear transplantation
A technique in which the nucleus of one cell is placed into another cell that already has a nucleus or in which the nucleus has been previously destroyed.
reproductive cloning
Using a somatic cell from a multicellular organism to make one or more genetically identical individuals.
stem cell
Unspecialized cell that can both reproduce itself indefinitely and differentiate into specialized cells of one or more types.
morphogenesis
The process by which an organism takes shape and the differentiated cells occupy their appropriate locations.
cytoplasmic determinants
Maternal substances in egg that influence the course of early development.
induction
The process by which neighboring cells can influence the determination of a cell.
transcription factors
Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.
homeotic genes
Genes that determine basic features of where a body part is.
hox genes
Class of homeotic genes. Changes in these genes can have a profound impact on morphology.
pattern formation
The development of a spatial organization of tissues and organs.
microRNA (miRNA)
Small, non-coding RNA molecules that function in regulation of gene expression by binding to and destabilizing target mRNAs.
apoptosis
Programmed cell death.
phototropism
Growth of a plant shoot toward or away from light.
photoperiodism
A plant's response to seasonal changes in length of night and day.
circadian rhythms
The 24-hour biological cycles found in humans and many other species.
quorum sensing
The ability of bacteria to sense the presence of other bacteria via secreted chemical signals.
innate behavior
A behavior that is developmentally fixed.
estivation
Summer torpor. Enables animals to survive long periods of high temperatures and scarce water supplies.
resource partitioning
Differentiation of niches that enables similar species to coexist.
lichen
Symbiotic association between a fungus and a photosynthetic partner, usually green algae or cyanobacteria.
mycorrhizae
A symbiotic association between a fungus and the roots of a plant.
cell division
The process in reproduction and growth by which a cell divides to form daughter cells.
genome
The ordering of genes in a haploid set of chromosomes of a particular organism.
binary fission
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size.
somatic cell
Any of the cells of a plant or animal except the reproductive cells.
chromosomes
Threadlike structures made of DNA molecules that contain the genes.
chromatin
The readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins.
sister chromatids
Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.
centromere
The region of the chromosome that holds the two sister chromatids together during mitosis.
centriole
In animal cells, a cytoplasmic organelle that organizes the mitotic spindle fibers during cell reproductions.
cell cycle
Series of events that cells go through as they grow and divide.
mitosis
Cell division in which the nucleus divides into nuclei containing the same number of chromosomes.
M phase
Mitosis and cytokinesis.
checkpoints
The cell cycle is directed by these internal controls.
replication
Replication of DNA during S-phase of interphase.
alignment
Alignment of chromosomes prior to separation.
separation
Separation of chromosomes.
cytokinesis
Division of the cytoplasm to form two separate daughter cells.
interphase
Period of the cell cycle between cell divisions.
S phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
G1 phase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
G2 phase
The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
G0 phase
When a cell specializes, it often enters into a stage where it no longer divides, but it can reenter the cell cycle when given appropriate cues.
cancer
Disease that results from disruptions of cell cycle control.
mitotic spindle
An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.
centrosome
A structure in animal cells containing centrioles from which the spindle fibers develop.
kinetochore microtubules
Connects the centrosome with the kinetochore in the centromere region of the chromosome.
kinetochore
A specialized region on the centromere that links each sister chromatid to the mitotic spindle.
asters
Microtubules and fibers that radiate out from the centrioles.
metaphase plate
Plane midway between the two poles of the cell where chromosomes line up during metaphase.
cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.
cell plate
A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.
density dependent inhibition
The arrest of cell division that occurs when cells grown in a laboratory dish touch one another.
growth factors
Regulatory proteins that ensure that the events of cell division occur in the proper sequence and at the correct rate.
Cdk
Complex of cyclin and kinase.
MPF
A cyclin-Cdk complex that causes the cell to move from interphase into mitosis.
cleavage
The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; specifically.
allele
One of the alternative forms of a gene that governs a characteristic, such as hair color.
alteration of generations
The alteration of two or more different forms in the life cycle of a plant or animal.
autosomes
Chromosomes that are not directly involved in determining the sex of an individual.
asexual reproduction
One parent produces a genetically identical offspring by mitosis.
chiasmata
X-shaped regions where crossing over occurred.
crossing over
Nonsister chromatids exchanging DNA segments.
diploid cell
Has two sets of chromosomes.
fertilization
Union of gametes.
gametes
A haploid cell such as an egg or sperm that unite during sexual reproduction to produce a diploid zygote.
genes
Units of heredity made up of DNA.
haploid
One set of chromosomes.
homologous chromosomes
Pair of chromosomes that are the same size, same appearance and same genes.
karyotype
Photograph of chromosomes grouped in order and in pairs.
life cycle
All of the events in the growth and development of an organism until the organism reaches sexual maturity.
locus
The specific site of a particular gene on its chromosome.
mutations
Random errors in gene replication that lead to a change in the sequence of nucleotides; the source of all genetic diversity.
nonsister chromatids
Different chromatids (maternal and paternal) of the same chromosome.
recombinant chromosomes
Chromosomes that carry genes from each parent. http://o.quizlet.com/Hk486OhrBK7sHtaml1nnmg.png
sex chromosomes
X and Y chromosomes.
sexual reproduction
When two parents give unique combination of genes to offspring.
synapsis
Homologous chromosomes pair up, aligned gene by gene.
tetrad
A pair of chromosomes form tetrads made up of four chromatids.
zygote
Fertilized egg; carries one set of chromosomes from each parent.
variation
Is demonstrated by the differences in appearance that offspring show from parents and siblings.
platelet-derived growth factor (PDGF)
One of the numerous proteins that regulate the cell cycle.
law of independent assortment
The random distribution of the pairs of genes on different chromosomes to the gametes.
law of segregation
Allele pairs separate or segregate during gamete formation, and randomly unite at fertilization. Due to separation of homologous chromosomes in Meiosis I.
character
A heritable feature that varies among individuals.
trait
Each variant of a character.
true-breeding
Organisms that, when reproducing, create offspring of all the same variety.
hybridization
The crossing of two different true-breeding parents.
P generation
The name for the true-breeding parents.
F1 Generation
The hybrid offspring of true-breeding parents.
F2 Generation
After the self-pollenization, of the F1 generation, this is produced.
The Law of Segregation
Two alleles separate during gamete formation and end up in different gametes because they are on homologous chromosomes.
dominant allele
An allele whose trait always shows up in the organism when the allele is present.
recessive allele
An allele that is masked when a dominant allele is present
Punnett square
A diagram for predicting the allele composition of offspring from a cross between individuals of known genetic makeup.
homozygous
An organism having a pair of identical alleles for a character, either dominant or recessive.
phenotype
An organism's traits.
genotype
An organism's genetic makeup.
testcross
The result of breeding a recessive homozygote with an organism of dominant phenotype but unknown genotype.
monohybrids
Parents that are heterozygous for one character.
dihybrids
Parents that are heterozygous for two characters.
multiplication rule
To determine the probability, we multiply the probability of one event by the probability of another.
addition rule
Considering mutually exclusive events, the probability of both occurring is the sum of the probabilities of each event.
complete dominance
When the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
codominance
When which the phenotypes of both alleles are exhibited in the heterozygote.
incomplete dominance
Creates a blended phenotype; one allele is not completely dominant over the other.
pedigree
A diagram that shows the occurrence of a genetic trait in several generations of a family.
cystic fibrosis
A genetic disorder that is present at birth and affects both the respiratory and digestive systems.
chorionic villus sampling CVS
Prenatal diagnostic technique that involves taking a sample of tissue from the chorion.
amniocentesis
A fetal test in which amniotic fluid from a pregnant woman is extracted to aid in the diagnosis of fetal abnormalities.
nondisjunction
A failure of paired homologous chromosomes to separate during meiosis which results in an abnormal chromosome number.
Down syndrome (trisomy 21)
A genetic disorder caused by the presence of all or part of a third copy of chromosome 21.
Kleinfelter's syndrom
A genetic disorder in which there is at least one extra X chromosome to a standard human male karyotype,
Tay-Sachs disease
A human genetic disease caused by a recessive allele that leads to the accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after birth.
Huntington's disease
Genetic disorder that causes progressive deterioration of brain cells. caused by a dominant allele. symptoms do not appear until about the age of 30.
sickle-cell disease
Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape.
heterozygote advantage
When the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype.
Human Genome Project (HGP)
The international scientific research project with the goal of determining the sequence of base pairs in human DNA and identifying and mapping the total genes of the human genome.
linked genes
Genes located on the same chromosome that tend to be inherited together in genetic crosses.
genetic recombination
The regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents.
parental types
Offspring with a phenotype that matches one of the parental phenotypes.
recombinant types
Offspring who have inherited new combinations of genes and have phenotypes that don't match either parental phenotypes.
crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
genetic map
An ordered list of the genetic loci along a particular chromosome.
linkage map
A genetic map based on recombination frequencies.
map units
A measurement of the distance between genes; one map unit is equivalent to a 1 percent recombination frequency.
polygenic traits
Traits are the product of multiple genes and/or physiological processes.
quantitative characteristics
Traits that vary continuously (such as height or weight).
XY system
A sex determination system in which females have two of the same kind of sex chromosome and males have two different ones.
sex chromosome
Either of a pair of chromosomes that combine to determine the sex and sex-linked characteristics of an individual.
sex linked genes
Genes located on the sex chromosomes.
X linked genes
Genes found on the X chromosome.
barr body
A dense body formed from a deactivated X chromosome.
genomic imprinting
Variation in phenotype depending on whether an allele is inherited from the male or female parent.
sex limited
When expression of a gene depends on the sex of the individual.
sexual dimorphism
A phenotypic difference between males and females of the same species.
nonnuclear inheritance
Occurs when genes that are not part of a nuclear chromosome are passed on from parent to offspring.
regulatory gene
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
operon
A unit of genetic function common in bacteria and phages, consisting of coordinately regulated clusters of genes with related functions.
activator
A protein that binds to DNA and stimulates transcription of a specific gene.
inducer
A specific small molecule that inactivates the repressor in an operon.
operator
Region of DNA that controls RNA polymerase's access to a set of genes with related functions.
promoter
Nucleotide sequences that allow the genes of an operon to be transcribed.
terminator
Nucleotide sequences that mark the end of a gene or operon.
repressor
A protein that suppresses the transcription of a gene.
enhancer
Short regions of DNA that can be bound with proteins to enhance transcription.
Trp operon
An example of a repressible operon.
Lac operon
An example of an inducible operon.
repressible operon
An operon under negative control. It is usually "on" but can be turned "off".
inducible operon
An operon under positive control. It is usually "off" but can be turned "on".
transcription factors
Proteins that bind to specific DNA sequences or other regulatory proteins that promote or block RNA polymerase.
contact inhibition
Normal somatic cells will become growth inhibited when they encounter another cell.
cytokines
A diverse group of soluble molecules which act as hormonal regulators or signaling molecules and help in cell signaling.
SRY gene
Y linked gene that triggers the male sexual development pathway in animals.
gibberellins
Plant hormones in the seed embryo that signal starch hydrolysis during germination.
morphogens
Signaling molecules that stimulate cell differentiation and development.
p53
Molecule that prevents mitosis in cells with damaged DNA. Changes in its activity can result in cancer.
signal transduction
The process by which a signal on a cell's surface is converted into a specific cellular response.
local regulators
These regulators influence cells in the vicinity of them.
hormones
Circulating chemical signals that are formed in specialized cells, travel in body fluids, and act on specific target cells.
ligand
A molecule that specifically binds to another molecule, often a larger one.
protein kinase
The enzyme that transfers phosphate groups from ATP to protein.
adenylate cyclase
Activated by a G-protein. Converts ATP to cyclic AMP in response to an extracellular signal.
protein phosphatases
Enzymes that can rapidly remove phosphate groups from proteins.
second messengers
Small, non-protein water soluble molecules or ions that send messages throughout the cells by diffusion.
inositol triphosphate (IP3)
Produced by cleavage of a certain kind of phospholipid in the plasma membrane.
reception
The target cell's detection of a signal molecule coming from outside the cell.
transduction
The binding of the signal molecule changes the receptor protein in some way.
response
The transduced signal finally triggers a specific cellular response.
G-protein-linked receptor
A plasma membrane receptor that works with the help of a G-protein.
receptor tyrosine kinase (RTK)
A receptor with enzymatic activity that can trigger more than one signal transduction pathway at once, helping the cell regulate and coordinate many aspects of cell growth and reproduction.
ligand-gated ion channel
Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
diacylglycerol (DAG)
A second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane.
epinephrine
adrenaline
cyclic AMP (cAMP)
secondary messenger that activates protein kinases and initiates phosphorylation cascades.
plasmodesmata
An open channel in the cell wall of plants through which strands of cytosol connect from adjacent cells.
gap junctions
In animal cells, pores formed from connected membrane proteins that allow molecules to pass directly from cell to cell.
paracrine signaling
Type of cell signalling where cells communicate over short distances by using local regulators that target cells in the vicinity of the emitting cell.
endocrine signaling
Type of cell signalling where signals released by one cell type can travel long distances to target cells of another cell type.
growth hormone
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.
thyroid stimulating hormone (TSH)
Hormone made by the anterior pituitary that regulates the production of T3 and T4 hormones produced by the thyroid gland.
conformation change
change in shape
acetylcholine
A neurotransmitter that, among its fuctions, triggers muscle contraction.
signal
A behavior that causes a change in another animal's behavior.
communication
The reception of and response to signals.
innate behavior
Behavior performed correctly and in the same way by all individuals of a species, without previous experience.
learned behavior
A behavior that has been learned from experience or observation.
promiscuous
A type of relationship in which mating occurs with no strong pair-bonds or lasting relationships.
monogamy
A type of relationship in which one male mates with one female.
polygyny
A type of relationship in which one male mates with many females.
polyandry
A type of relationship in which one female mates with many males.
intersexual selection
When members of one sex choose mates on the basis of particular characteristics.
Intrasexual selection
A direct competition among individuals of one sex for mates of the opposite sex.
optimal foraging theory
The basis for analyzing behavior as a compromise of feeding costs versus feeding benefits.
cooperative behavior
Behavior that tends to increase the fitness of the individual and the survival of the population.
Central Nervous System (CNS)
Includes the brain and spinal cord.
Peripheral Nervous System (PNS)
The sensory and motor neurons that connect the CNS to the rest of the body.
cell body
Contains most of a neuron's organelles and its nucleus.
dendrites
highly branched extensions that receive signals from other neurons
axon
Long nerve fiber that conducts away from the cell body of the neuron.
synapse
The junction between two neurons or between a neuron and a muscle.
neurotransmitters
Chemical messengers that cross the synaptic gaps between neurons.
presynaptic cell
The transmitting neuron in a synapse.
postsynaptic cell
The neuron, muscle, or gland cell that receives the signal from a neuron.
membrane potential
The voltage across a cell's plasma membrane.
resting potential
The membrane potential of a neuron that is at rest.
depolarization
The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.
voltage-gated ion channels
Channels that open or close in response to a change in the membrane potential.
action potential
A neural impulse; a brief electrical charge that travels down an axon.
repolarization
Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.
threshold
The minimum membrane potential that must be reached in order for an action potential to be generated.
myelin sheath
A layer of electrical insulation that surrounds the axon.
oligodendrocytes
Type of glial cell in the CNS that wrap axons in a myelin sheath.
Schwann cells
Type of glia in the PNS, Supporting cells of the peripheral nervous system responsible for the formation of myelin.
nodes of Ranvier
Gaps in the myelin sheath to which voltage-gated sodium channels are confined.
synaptic vesicles
Membrane-bounded compartments in which synthesized neurotransmitters are kept.
synaptic cleft
The narrow gap that separates the presynaptic neuron from the postsynaptic cell.
acetylcholine
Common vertebrate neurotransmitter, especially in neuromuscular junctions.
serotonin
A neurotransmitter that affects hunger,sleep, arousal, and mood.
dopamine
A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.
epinephrine
Neurotransmitter secreted by the adrenal medulla in response to stress. Also known as adrenaline.
norepinephrine
A precursor of epinephrine that is secreted by the adrenal medulla and also released at synapses.
GABA
An inhibitory neurotransmitter in the brain.
glutamate
The most common neurotransmitter in the brain. Excitatory.
endorphins
Natural analgesics that decrease pain perception.
neuron
Structural and functional unit of nervous system.
effector cells
Muscle cells or gland cells that carry out the body's response to stimuli.
astrocytes
Provide structural and metabolic support for neurons.
glial cells
Cells in the nervous system that support, nourish, and protect neurons.
white matter
Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.
grey matter
The portions of the central nervous system that are abundant in cell bodies of neurons rather than axons. Unmyelinated.
autonomic nervous system
the part of the nervous system of vertebrates that controls involuntary actions of the smooth muscles and heart and glands
cerebrum
Largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory.
forebrain
The largest and most complicated region of the brain, including the thalamus, hypothalamus, limbic system, and cerebrum.
midbrain
Region between the hindbrain and the forebrain; it is important for hearing and sight.
hindbrain
The posterior portion of the brain including the cerebellum and brainstem.
cerebral cortex
Interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center.
brainstem
The oldest part and central core of the brain, responsible for automatic survival functions.
cerebellum
The "little brain" attached to the rear of the brainstem that helps coordinate voluntary movement and balance.
thalamus
Major input center for sensory information going to the cerebrum and the main output center for motor information leaving the cerebrum.
cerebral hemispheres
The right and left halves of the cerebrum.
sodium-potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell.
alpha glucose
beta glucose
cellulose
Carbohydrate component of plant cell walls.
starch
Storage polysaccharide of plants.
glycogen
Extremely branched polymer of glucose.
chitin
Polysaccharide found in arthropod exoskeletons.
-ose
Suffix of a sugar.
tryiacylglycerol
steroids
Made of 4 rings of carbon.
cholesterol
Steroid common in cell membranes, also in many hormones.
peptide bond
Bonds that connect amino acids.
disulphide bridges
Reinforce tertiary structure.
primary structure
Chain of amino acids.
secondary structure
Either an alpha helix or beta pleated sheet.
tertiary structure
Results from interactions between side chains.
quaternary structure
Results from 2 or more polypeptide subunits.
-in
Suffix of a protein.
phosphodiester bonds
Bonds between phosphate group and pentose sugar in nucleic acids.
synthesis
To put together.
digestion
To break apart.
dehydration synthesis
Condensation reaction where molecules are connected by loss of a water molecule.
hydrolysis
Breaking down complex molecules by the chemical addition of water.
condensation reaction
Another name for dehydration synthesis.
side chain
Another term for R-group. A variable group that determines the unique chemical properties of a particular amino acid.
alpha helix
A spiral shape constituting one form of the secondary structure of proteins, arising from a specific hydrogen-bonding structure.
beta pleated sheet
One form of the secondary structure of proteins in which the polypeptide chain folds back and forth, held together by hydrogen bonds.
chaperonins
Protein molecules that assist the proper folding of other proteins.
saturated fatty acids
A fatty acid in which all carbons are connected by single bonds, thus maximizing the number of hydrogen atoms that can attach to the carbon skeleton.
unsaturated fatty acids
A fatty acid possessing one or more double bonds between the carbons. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.
monosaccharide
A simple sugar that is the basic subunit of a carbohydrate.
glycosidic linkage
A covalent bond formed between two monosaccharides by a dehydration reaction.
cisternae
Flattened, membrane-bound compartments that make up the Golgi apparatus.
genomic equivalence
All cells in an organism contain the same complement of genes. These are the same set of genes that are established in the fertilized egg.
species richness
The number of different species in a community.
species diversity
The number and relative abundance of species in a community.
exponential growth
Growth of a population in an ideal, unlimited environment, represented by a J-shaped curve.
logistic growth
Growth pattern in which a population's growth rate slows or stops following a period of exponential growth, forming an S-shaped curve.
carrying capacity (K)
Maximum population of a particular species that a given habitat can support over a given period.
limiting factors
Any biotic or abiotic factor that restricts the existence, numbers, reproduction, or distribution of organisms.
density dependent factors
A limiting factor of a population wherein large, dense populations are more strongly affected than small, less crowded ones.
density independent factors
Limiting factor that affects all populations in similar ways, regardless of population size.
r-selection
Also called density-independent selection. Characterized by many offspring with little or no parental care.
K-selection
Also called density-dependent selection. Characterized by few offspring with little or much parental care.
type I survivorship
Usually experience high survival in early and middle life, followed by a rapid decline in later life. Usually K-selected
type II survivorship
Experience roughly a constant mortality rate regardless of age. Prey animals such as birds can follow this pattern of survival.
type III survivorship
Experience the greatest mortality early on in life, with relatively low rates of death for those surviving. Usually r-selected.
age distribution
A model used in population geography that describes the ages and number of males and females within a given population.
Miller-Urey Experiment
Found that organic molecules can form in a strongly reducing atmosphere.
protobionts
Aggregates of abiotically produced molecules surrounded by a membrane.
liposomes
Membrane-bound droplets that form when lipids are added to water.
stromatolites
Oldest known fossils. Many layers of bacteria and sediment.
endosymbiotic theory
Ancestors of mitochondria and plastids was prokaryotes that came to live in a host cell.
serial endosymbiosis
Sequence of endosymbiotic events that led to ancestral eukaryote.
genetic annealing
Horizontal gene transfer between different bacteria and archae.
colonies
Collections of autonomously replicating cells.
RNA world hypothesis
Hypothesis that describes how the Earth may have been filled with RNA-based life before it became filled with the DNA-based life we see today.
ribozymes
RNA molecules that function as catalysts.
tetrapods
vertebrate animals having four feet, legs or leglike appendages.
continental drift
Motion of continents about Earth's surface on plates of crust floating on the hot mantle.
Pangea
A supercontinent that included all the landmass of the earth prior to the Triassic period, when it split into Laurasia and Gondwanaland.
extant
Still in existence.
Last Universal Common Ancestor (LUCA)
Hypothetical early cell, or group of cells, that gave rise to all subsequent life on Earth.
the three-domain system
Domains Bacteria, Archae, and Eukarya.
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