cohesion species concept
defines a species as a group of organisms that can exchange genetically; concentrates on mechanisms that maintain species as discrete phenotypic entities
What is a species?
Difficult to define. Ideally should allow one to distinguish organisms that are on independent evolutionary "paths"
Whati sthe problem with using the morphological species concept to compare orgainisms in the fossil record?
morphological differences do not necessarily indicate genetic differences
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier (allo means different, patric means homeland). EX: maruspials in austrailia have no placenta mammals, marsupials everywhere else does
What are some examples of geographical distrubances that may cause allopatirc speciation?
forest fire, earthquake, formation of a canyon, continental drift
What are three mechanisms by which allopatric speciation occurs?
founder effect, genetic drift will continue, selection pressures of the new enironment
What is important about the physical barrier of allopatric speciation?
it prevents intermating between individuals in the two populations
The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present. This happens in plants by polyploidy and some amphibians.
An organism having more than two sets of chromosomes, all of which were derived from the same species (self-fertilization).
having more than 2n sets of chromosomes which are derived from two different species
___ is cause by a mistakes in either mitosis or meiosis which results from a nondisjunction of chromosomes.
What makes something a species?
populations that interbreed and produce fertile offspring; breeding takes place in a wild, free-range condition
How does speciation begin?
a small population must be isolated to interrupt gene flow (geographical isolation), genetic divergence, reproductive isolation
An evolutionary pattern in which many species evolve from a single ancestral species
Geographically isolated populations become separate species when they are no longer able to ___ or when the resulting offspring are not viable and/or fertile.
What are some conditions that allow adaptive radiation to occur?
a population invades an island that contains a number of unexploited niches and variation in environmental conditions; when an opportunity of unexploited niches and varying habitat enable a single species to diversify into several new species.
Name 5 prezygote mechanisms.
isolation by habitat, behavioral isolation (courtship ritual), temporal isolation (time factors/seasonal), mechanical isolation (reproductive organs that don't fit), gametic isolation (recognition between sperm and egg)
a selective breeding method in which 2 genetically different individuals are crossed
What must happen for a new species to form?
two different populations that can't reproduce with each other (isolating mechanisms between populations
Two populations are classified as separate ___ when they can't produce fertile offspring in wild, free-ranging conditions.
Give some examples of some species that have evolved.
finches, mustard plant, marsupials -> opossum, lizard -> snake, dinosaurs -> birds, reptiles -> amphibians, oats, cotton, potatoes, tobacco, wheat
What are two theories which present different views as to how species arise?
gradualism, punctuated equilibrium
a model of evolution in which gradual change over a long period of time leads to biological diversity
pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
evolution on the smallest scale—a generation-to-generation change in the frequencies of alleles within a population (natural selection, mutation, gene flow, genetic drift)
large-scale evolutionary changes that take place over long periods of time (a bunch of microevolutions, speciation starts macroevolution change)
A pattern of evolutionary change that produces biological diversity by budding one or more new species from a parent species that continues to exist; also called branching evolution.
biological species concept
definition of a species as a population or group of populations whose members can breed with one another in nature and produce fertile offspring
What are some limitations to the biological species concept?
asexual organisms, fossils (no way to evaluate the reproductive isolation of these)
What are some reasons for the extinction of a species?
habitat destruction, interbreeding, hybridization, env. pollution, catastrophes, competition, predators, disease, hunting/collecting, natural selection
What is the role of natural selection on extinction?
a species could find that it does not have traits within its gene pool to survive changes in the environment, and a sudden shift in the environment, such as a loss of habitat, a species may not been able to live long enough to reproduce; the extinct organisms were not able to adapt to the environment, and only the fittest survived
tentative answer to a well-framed question; educated guess; must be testable and falsifiable
use passive voice, verbs are present tense, scientific names are italicized, data is plural from datum, spectra is plural from spectrum, species is singular and plural, #'s greater than ten are associated with measurements should be written as numerals, number associated with a measurement should not start with a sentence, metric measurements should be abbreviated without periods
an element that has the same number of protons but the neutrons increase; they behave identically in chemical reactions
one which the nucleus decays and spontaneously gives off particles and energy
negative charge; react in chemical reactions; attracted to positive nucleus; goal is to fill electron shells; when loose energy they are pulled toward nucleus; when gain energy they move to outer shells
outermost shell of atom; behavior of atom depends mostly on the number of electrons in the outermost shell of atom
elements found in group 18, do not usually form compounds because atoms do not usually gain, lose, or share electrons. (unreactive)
polar covalent bonds
one atom is bonded to a more electronegative atom, the electrons of the bond are not shared
where a more electronegative atom strips electrons away from its partner; transfer electrons
Compounds formed by ionic bonds are called ionic compounds or ______, which are often formed in nature as crystals.
reversible chemical reaction, the points where the reactants decompose and break down to meet the same amount that is formed
What atom is the basis of most biological molecules?
Carbon (enters the biosphere through plants, which use the sun to make CO2 in the atmosphere)
organic molecules consisting only of carbon and hydrogen; they are part of petroleum because of fossil fuels of living organisms long ago; they release a lot of energy; they do not dissolve in water
compounds that have the same numbers of atoms of the same element but have different structures and hence different properties
What are the six functional groups most important in the chemistry of life?
hydroxyl, carbonyl, amino, sulfhydryl, carboxyl, phosphate
What are the four main classes of large biological molecules?
carbohydrates, lipids, proteins, nucleic acids
Which of the four main classes of large biological molecules are polymers? Which are not?
Polymers: carbohydrates, nucleic acids, proteins. Not polymers: lipids
What is an example of a polysaccharides?
many sugars; macromolecules (starch, glycogen, dextran, cellulose, chitin)
structural polysaccharide that is a major component of tough walls that enclose plant cells
biological molecule is insoluble to water, consists of mostly hydrocarbons, and has no polymers
large molecules that are not polymers and are assembled from smaller molecules by the dehydration process; combined of glycerol and 3 fatty acids
similar to fat but has only 2 fatty acids attached to glycerol rather than 3; the 3rd hydroxyl group of glycerol is joined to a phosphate group, which has a negative electrical charge
account for more than 50% of dry mass of most cells; consists of one or more polypeptides folded and coiled into specific formations; functions are storage, transport, protect, contractile, structural (shape determines function)
polymers of amino acids; proteins are all polymers constructed from the same set of 20 amino acids
type of protein that regulates metabolism by acting as catalysts; work horses of cell by running and carrying out the processed of life
DNA and RNA; Polymers assembled from individual nucleotides; used to store and transmit hereditary, or genetic, information; the two kinds of nucleic acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
In a ____ cell, ribosomes are located in the cytoplasm, but DNA resides in the nucleus.
What conveys the genetic instructions from building proteins from the nucleus to the cytoplasm?
messenger RNA (mRNA)
___ cells lack nuclei, but they still use the RNA to send a message from the DNA to the ribosome.
What are the four nitrogenous bases of nucleic acids of DNA?
A (adenosine), T (thymine) G (guanine), C (cytosine); A - T, G - C
What are the four nitrogenous bases of nucleic acids of RNA?
A (adenosine), U (uracil) G (guanine), C (cytosine); A - U, G - C
consists of 4 hydrogen bonded to a carbon (CH4, methane); can have four bonds per carbon atom; building blocks from many complex molecules making up organisms
An atom with a high electronegativity is more likely to become a ____ ion.
negative (gain electrons)
Electronegativity values ___ moving up and to the right of the periodic table. Thus O is the most electronegative over N. H is the least electronegative.
relatively weak attraction between a partially positive H of one molecule and the partially negative atoms of another molecule; two most common are H-O and H-N. DNA molecules have these bonds
van der wals
very weak bond; happens between tow molecules that have no polar molarity (ex: tar and oil); non-polar (carry no charge) and very tightly packed
Received the 1954 Nobel Prize from his work on genetics and atomic structure of proteins and hemoglobin; he proposed a 3 stranded DNA molecule
Watson and Crick
(1) A=T, G=C, (2) Measurements: 0.34, 3.4, 2.0, 10 bases per turn of the helix (3) bond of pyrimidines (C,T, single ring) and purine (A, G, two ring) are H-bonds
5 end means the 5 carbon end is facing up; 3 end means the 3 carbon end is facing up; phosphates are covalently linked to the 5 carbon
DNA; does NOT contain oxygen and is a pentose (5 carbon) connected to the nitrogen base
Meselson and Stahl (1958)
devised experiments that would test the way that DNA replicates itself; used differential centrifugation; made DNA heavy to trace it; *DNA replication is semi-conservative*
a process by which a large molecule is constructed; DNA forms new strands this way; endergonic process (requires energy) and is not spontaneous
enzyme that catalyzes polymerization of new DNA strands (it does not create the energy to start the reaction)
Where is the energy provided from that is needed to polymerize?
by breaking one of the double phosphate bonds of of the triphosphate nucleotide
The newly sythesized DNA strand is ___ with the parental strand. The reason is that the 5' to 3' orientation of the parental strand is opposite of the new strand.
What does eukaryotic cells use to greatly speed up replication at multiple sites?
What are the steps to DNA replication?
1. DNA forms replication forks, 2. helicase unravels DNA at the orgin of replication, 3. single strand binding protein pull and keep the strands apart, 4. DNA polymerase reads parent strand in 3' to 5' direction, 5. New strands are constructed in a 5' to 3' direction
DNA replication is ___continuous in one strand and ___ discontinuous in the other.
DNA Polymerase can only polymerize reactions in the ____3' to 5' direction of the template DNA strand. It can only add in the ____ direction. It also repairs damaged DNA.
3' to 5'; 5' to 3'
What are some things that primase does?
1. synthesize an RNA primer, 2. use a DNA template, 3. initiate a new polynucleotide strand complimentary to a template strand
Why can DNA polymerase only read in the 3' to 5' directions?
it is sensitive to shape of the OH part of the nucleotide
the strand that grows discontinuously and away from the replication fork; build in the 5' to 3' direction; can only add to 3' OH group of an existing strand; part DNA and part RNA
named for Reiji Okazaki who discovered that the lagging strand is synthesized discontinuously
DNA polymerase 1
enzyme that assists in removing RNA primers from the lagging strand and replaces them with DNA; it is a exonuclease because it removes RNA primers
Who does the ligase and polymerase 1 fragments work together to remove RNA and stick together okazaki fragments?
The polymerase 1 lands on the RNA primer and acts as a exonuclease and takes the RNA out. Polymerase 1 adds deoxyribo nucleotides. Ligase joins the two okazaki fragments together
repeating non-coding sequences of nucleotides found at the end of DNA strands to protect the coding sequences.
When the last RNA primer on the lagging strand is removed, there is no ___ group for DNA polymerase to attache to.
an enzyme that can polymerize telomere sequences; counteracts the shortening of telomeres; can be found in cells that replicate many times such as bone marrow and germ cells (gametes), and cancer cells.
The lagging stand ends with an RNA primer and when it is removed by polymerase 1, the strand is shorter. ___ fills in the gap at the end.
What are some features of prokaryotic cells?
boxy/square, cytoplasm, ribosomes, nuclear body, DNA (circular in nucleoid), plasmid (small loops of DNA), cell membrane, nucleoid, cell wall, capsule, flagellum, no membrane bound organelles --- Bacteria and Archaea
What are some features of eukaryotic cells?
cell membrane, membrane bound organelles, rod-like chromosomes, cytoplasm, nucleus, ribosomes, rough and smooth endoplasmic reticulum, Golgi body, vacuoles, lysosomes, cytoskeleton, centriole, cilia, microvilli, cell wall (plants only), mitochondria, chloroplasts (plants only)
Similarities of Eukaryote and Prokaryote
Note: The difference is the presence vs. absence of membrane bound organelles.
casing around outside of cell and it's internal organelles are made of a phospholipid bilayer
the eukaryotic cell is divided into compartments separated by membranes; it is key to efficiency in cell metabolism and allows for specialization
outside of cell (animal cells - outside of cell; plant cells - under cell wall); function is selective contact with the environment; allows food and wastes to exit and enter the cell (aka cell membrane)
Surface area in cells
surface-to-area volume ratios set limitations on cell size; surface area of plasma membrane is very important in cells; a higher surface-area-to-volume ratio is more efficient in cellular activity to keep up with the needs of the interior of the cell
cytoplasmic extensions of the cell membrane; hairlike appendages; increases the surface area of the cell
Why is the fluid mosaic model called a double layer?
it has two layers because of the hydrophobic tails and the hydrophilic heads of the phospholipids
Fluid mosaic model
basic membrane structure consisting of a phospholipid bilayer embedded with various proteins; the fluids are somewhat fluid, allowing the movement of proteins within the phospholipids (NOTE: bilayer and double layers are the same thing)
A fatty acid chain has a long chain of carbons and ends with a ___ group.
CH3, which makes it nonpolar (hydrophobic)
charged (hydrophilic) head made of phosphate; non-charged (hydrophobic) tails made of fatty acids; make up cell membranes
macromolecules made upon of one or more protein chains; hydrophilic head and hydrophobic middle that float in the phospholipid bilayer ("sea of fat"). They are made of a polypeptide chain of amino acids and peptide bonds; synthesized in cytosol
where all the initial activity that governs the cell occurs; contains DNA; has a nuclear envelope (double-lipid bilayer)
doubled-up phospholipid bilayer that surrounds the nucleus; has pores surrounded by proteins used to transport called pore complex; has nuclear lamina, which is a series of proteins that holds the nuclear together and helps keep its shape; has ribosomal subunits
functions in reinforcing the shape of the nucleus; layer of fibrous proteins on the inner layer
The organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus; site of ribosomal subunit assembly
combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell
___ carries the code; ___ carries the message; ___ carries out work and function
DNA; RNA; Protein
What are the plant and animal cell similarities?
Both have DNA, ribosomes, cytoplasm, cell membrane, cytoskeleton, mitochondria, golgi apparatus; endoplasmic reticulli, nucleus, nucleolus
What are the plant and animal cell differences?
Animal cell: can be all kinds of shapes; Plant cell: cell walls, chloroplasts, central vacuole, boxy/square
part of the cytoskeleton that contains keratin and give extra strength to the cell
cilia and flagella
part of cytoskeleton; consists of parts of microtubules arranged in a 9 + 2 arrangement
part of cytoskeleton; located at the base of every cilium and flagellum; structurally identical to a centriole; eukaryotic cell organelle consisting of fused triplet mircrotubules
plants are not the only cells that have it; there are other organisms, both unicellular and multicellular, that have it; bacteria, fungi, and plants have it
what bacterias' cell walls are made of; polymers of modified sugars cross-linked by short polypeptides (chains of amino acids)
structural polymer consisting of strands of glucose with alternate beta linkages, which is insoluble and helps toughen the cell wall
How do cells grow?
1. cells secrete cellulose from plasma membrane, forming a primary cell wall that is elastic permitting growth and division, 2. Pectin starts forming and strengthening the cell wall, 3. Secondary cell wall can be composed of 2-3 more layers and will have a secretion of celluloses and lignin in between the primary and secondary cell walls.
All cells have plasma membrane, but only __ cells and certain ___ organisms have cell walls
cytoplasmic channels that run through adjacent plant cells (NOTE: plant cells have the ability to share cytoplasm)
The ______ is a matrix of cellulose and pectin, with cellulose providing structural support and pectin providing the "glue" to join neighboring cells.
What is a summary of cell functions?
DNA makes RNA; RNA leaves the nucleus and makes protein in the ribosomes; proteins control the function of the cell
What is a network of membrane enclosed canals that are responsible for the formation and secretion of proteins? It also aids in the creation of proteins.
What is closely associated with the nucleus and in some spots it's continuous with the nucleus is part of the endomembrane system, and when a closer look at the it reveals that some portions of the outside are covered with ribosomes?
Endoplasmic Reticulum (ER)
A network of canal like tubes and flattened sack structures throughout the cell
Endoplasmic Reticulum (ER)
What are some of the functions of the rough ER?
It's a big factory; it's responsible for processing and altering proteins to tertiary structure; protein comes off of the ribosomes and enters the lumen through the pore; in the primary structure, the proteins convert: primary -> helixes -> beta pleated sheets -> tertiary structures
Proteins may be incorporated in to the ER membrane, becoming part of the___.
Endoplasmic reticulum (ER)
What is covered in ribosomes, converts proteins from primary to tertiary structures, may add portions of carbs to proteins to create glycoproteins, and the proteins itself may be incorporated into the ER itself?
What lacks ribosomes, is the process center for proteins, is attached to the rough ER, synthesizes phospholipids and steroids?
What is the detoxification process in liver cells?
toxins end up in smooth ER for detoxification and to be more soluble so you body can rid them, the more you liver detoxifies the more smooth ER it will produce to detoxify faster, excessive amounts of smooth ER can cause problems like the improper breakdown of substance needed by the cell, like antibiotics
The folds of the ER are ___. They are flattened membrane bound compartments found in organelles such as the ER and Golgi's apparatus.
Proteins manufactured in the ___ ER are not secreted into the cytoplasm. Cytoplasmic proteins are produced on free ribosomes within the cytosol. Proteins manufactured in the ___ ER are destined to be either membrane proteins or secretory proteins.
The ____ system allows certain proteins to be created, modified, and transported out of the cell with out ever coming into contact with the cytosol.
The ___ makes proteins ready for other jobs inside or outside of the cell by packaging proteins in a transport vesicle and preparing them for the next step. The cis face faces the ER and the trans face faces the plasma membrane.
The process of releasing materials through the plasma membrane; the protein leaves the Golgi at the trans face.
How do proteins enter and leave the Golgi?
protein leaves ER in transport molecule and fuses with the cis face; protein travels fro cristernia via vesicles for outside transport; protein leaves from tans face of Golgi in a vesicle.
The Golgi consists of stacked membranes. The cytosolic side of the ____ ER is studded with ribosomes. Vesicles are membrane-bound compartments of cytoplasm.
Packing molecules will be found on the ___ face of the Golgi and provide recognition sites for transport vesicles from the ER.
The ___ face of the Golgi, the receiving side is typically near the ER. It receives transport vesicles from the ER. Transport vesicles pinch off the ___ face of the Golgi, which faces the plasma membrane of the cell.
Name the order of events of glycoprotein processing.
rough ER to transport vesicles -> cis region of Golgi -> trans region of Golgi
What starts a the ribosome, travels through the rough or smooth ER to be altered, and moves to the Golgi to be packaged and exported to be used in and out cell?
How are the proteins handled when they are needed within the cell?
they are contained in vesicles called lysosomes
___ have many functions in the cell, including enzymatic breakdown of food items (phagocytosis), organelle recycling (autophagy); breakdown of lipid in the brain, and are hydrolytic enzymes.
Engulfing extracellular particles by surrounding them with extensions of plasma membranes called "pseudopods."
An ___ (single-celled, eukaryotic protist) uses lysosomes in its everyday processes. It obtains nutrition through the process of phagocytosis.
A cell in the body called neutrophilis performs phagocytosis. They are ___ blood cells that engulf microbes.
The ___ fuses with the food vacuole allowing the enzymes to digest the extracellular particles obtained by the cell during phagocytosis. Now the food vacuole can move about the cell, distributing digested materials throughout the cell for various purposes.
Where does the following happen? 1) proteins enter ER and gets altered in the SER and RER, 2) transported through cis face and moved to Golgi, 3) Golgi packages the protein and sends away in the trans face
Why would water be enclosed in plant cells (H2O vacuoles) in a bag when cytosol is made of water?
for storage of: water during drought, proteins for later use, structural support, ions, toxic wastes
What is used by single-celled organisms to expel excess water from their interiors? It acts as a pump, to push the water that entered the the cell through osmosis and contracts to push the water out.
Which cell organelle contain enzymes that work by transferring hydrogen from a substrate to oxygen, thereby producing hydrogen peroxide as a by-product. Hydrogen peroxide is toxic to the cell, but these organelles also contain an enzyme that is capable of converting hydrogen peroxide to water.
Organelle in eukaryotic cells that serve as the site for aerobic respiration (energy release); "powerhouse"; not part of the endomembrane system; has a double membrane [outer and inner (cristae - inner membrane that increases surface area)]
Where is energy released in a cell, is only found in eukaryotic cells, and the outer membrane has less surface area than the inner membrane?
According to the ___ theory, mitochondria and chloroplasts are thought to have evolved from prokaryotic cells entering eukaryotic cells and suggests that mitochondria and chloroplasts arose from an ancestral prokaryote.
Remember: The inner membrane or the ____ of the mitochondria increases the surface area for reactions to take place.
How could a primitive cell bring in another one? This process may explain how endosymbiosis occurred.
What are some evidence that mitochondria may have originated as prokaryotes?
phagocytosis, the size is similar to prokaryotes, they have circular DNA like prokaryotes, they lack histones in DNA like prokaryotes, they have prokaryotic ribosomes, DNA homologous sequences are the same a prokaryotes, they can make proteins,
A group of plant organelles with various functions [ie, chromoplasts (stores pigments), amlyoplasts (stores starch), chloroplasts (center for photosynthesis)]
Which organelles of eukaryotic cells probably descended from endosymbiotic bacteria?
mitochondria and chloroplasts
What is acellular (no cells), has not metabolic process, is parasitic, has DNA or RNA, and cannot make protein?
You are not able to kill viruses with ___. It only kills bacteria's cell walls or their ribosomes. Viruses do not have cell walls or ribosomes.
What is the structure of a virus?
Bacteriophage structure, with DNA or RNA and a capsid (make of protein taken from host)
In the ________ a virus injects its reproductive material into a host cell and uses the host's enzymes and ribosomes to make copies of itself. Eventually, the cell lyses releasing free viruses to the cell.
What are the steps of the lytic cycle?
1. Attachment - Virus attaches to the cell wall at a receptor site
2. Entry - The cell wall is weakened by the viral enzymes, and the deoxyribonucleic acid (DNA) of the virus is injected into the host cell.
3. Replication - The DNA of the host cell is inactivated, and the viral DNA takes over making viral proteins and viral nucleic acid.
4. Assembly - Viral coats of protein (capsids) are assembled with the nucleic acids filling the cell with new virus particles.
5. Release - Enzymes dissolve the host cell membrane from within. THe cell then bursts open (cell lysis) and the newly formed virus particles are released, free to infect other bacterial cells.
In the _______ a virus incorporates its reproductive material into the host's genome where it is copied every time the host cell divides.
What are the steps of the lysogenic cycle
The lysogenic cycle is a viral replication cycle that involves the incorporation of the viral genome into the host cell genome.
The steps are:
1. Phage binds to the surface of an E. coli cell
2. Phage injects its DNA into the bacterial host cell
3. DNA forms a circle and either begins lytic or lysogenic cycle.
4. During a lysogenic cycle, DNA inserts by genetic recombination (crossing over) into a specific site on the bacterial chromosome and becomes a prophage.
How are the lysogenic and lytic cycle different?
the lytic cycle lyses and releases copies of the virus
the movement of molecules across the cell that does not require the expenditure of energy (ATP)
the movement of molecules from an area of high concentration to an area of low concentration
What are the determinants of the rate of diffusion?
concentration gradient, temperature, charge (solubility), diameter of the molecules
the passive transport of molecules down a concentration gradient with the aid of special transport proteins; ATP is not involved
What are the types of diffusion?
facilitated diffusion, passive transport, concentration gradients
What type of cell transport limits cell size, is only viable at short distances, and is responsible for molecules moving down a concentration gradient?
the passage of water across a membrane from an area of high concentration to low concentration; type of passive transport
Describe hypotonic for osmosis in plants.
more water in soil than plant; water is entering the plant through osmosis; the plant's cell water vacuoles are full "aka" *turgid*
Describe hypertonic for osmosis in plants.
water is lost from plant "aka" *plasmolysis*, which is the pulling away of the plasma membrane from the cell wall due to excessive water loss
Describe isotonic for osmosis in plants.
no water moving into the plant soil and plants have the same amount of water "aka" *flacid* water molecule
Why is saltwater not a thirst-quencher?
cell loses its water by osmosis; water will move from hypo to hyper trying to equalize the salt in the body, so water in you body will try to equalize the foreign salt in you body
due to pressure exerted by the flow of water through a semi-permeable membrane separating two solutions with different concentrations
You have 2 dialysis tubes, one 1% salt solution and the other contains a 10% salt solution. The first solution is ___ relative to the other.
a molecule that stores energy in its phosphate bond for later use. The "energy currency" of cells.
pumping of molecules against their concentration gradient with the expenditure of ATP; low -> high
Electrogenic pump (ion pump)
a protein that actively transports ions resulting in an ionic bond and voltage gradient. This gradient is a form of stored energy used to fuel other processes.
cells pump hydrogen ions agains a concentration gradient; the ions then enable the transport of other molecules back across the cell membrane; it is a coupled passage of 2 materials across a membrane
The resting membrane potential of a cell is maintained by _____. Cells maintain a differential charge across their membrane, which is a form of stored energy that cells can use to fuel energy requiring processes.
electrogenic pumps (ions pumps)
Which does not employ the use of a transport protein? facilitated diffusion, osmosis, active transport, sodium-potassium pump
What does not necessarily involve the transport of more than one substrate, expenditure of ATP is needed to drive the transport process, requires the use of transport proteins?
How do cells of the thyroid obtain iodine to produce thyroxin?
iodine is relatively rare in the blood and so it is actively pumped into the thyroid
Where does the sodium-potassium pump (NaK) occur?
nerve cells (neurons), which is impermeable to sodium and permeable to potassium
transmit info in the form of electrical signals; at rest they maintain a polarization across their cell membrane
the nerve cell is impermeable to NA+, but permeable to K and allows diffusion of K in the cell; NA+ rushes in the cell when the gated channels (active transport) open up due to an electrical impulse and turns the cell positive; the cell removes the Na+ to restore the resting potential
a change in the voltage (charge difference) across the membrane resulting from the movement of Na+ through channels into the cell
the voltage charge across the membrane of a cell while it's in an unexcited state
In order for the resting potential of a neuron to be restored, what must happen?
transport proteins must remove Na ions from the cell and import potassium into the cell
In a resting nerve cell, the interior is ___ relative to the exterior. The exterior is ___ positive relative to the interior (negative/positive).
the vesicle fuses and becomes one with the lipid bilayer; the export of mineral (especially proteins) from the cell by packaging them in vesicles and shipping them across the membrane.
the import of materials to the cell by infolding of the plasma membrane (types: phagocytosis, pinocytosis, receptor-mediated endocytosis)
"cell drinking"; the cell doesn't form pseudopods but a vesicle to take in fluid
vesicles form only when molecules are hooked into the receptor proteins. In special pits, receptors bind with specific materials; the pit them forms a vesicle.
The Golgi uses ___, cells secrete materials such as proteins by packaging them in a vesicle and shipping it across the membrane.
Vesicles that have formed from pinocytosis or phagocytosis often fuse with ___ inside the cell for digestion.
Many reaction occur in the mitochondria in the processes of making ATP. ____ do not have mitochondria, so these cells make ATP in the cytoplasm.
Biolog is the result of forces, both atomic and physical that occur within our bodies and our environment. Biology is about energy. 1) energy cannot be created or destroyed, only created, 2) energy transfer increases entropy
Bioenergetics: The law of thermodynamics
A measure of the randomness or disorder of a system. Life is a battle against constantly increasing entropy in the universe
the energy available to do work; G (free energy) = H (total energy in a system) - T (temperature) * S (entropy); G = H-ST; entropy reduces the amount of total energy that is available to do work; the more organized a system, the higher its free energy
ΔG = Gn (final) - Gi (initial); when ΔG is negative the reaction is exergonic or energy is released
ΔG = Gn (final) - Gi (initial); when ΔG is positive the reaction is endergonic or energy is put in
___ work to lower the activation energy required in a reaction, and its shape is critical in the process.
What are some enzyme characteristics?
temperature sensitive, pH sensitive, certain chemical inhibit enzymes, certain chemicals promote enzymes, certain enzymes will only react with certain substrates, enzyme reactions are reversible, shape is very important
change the rate of reaction, certain chemicals inhibit them, they are proteins that serve as catalysts to reactions, decrease the activation energy of reactions, sensitive to temperature and pH
In an _____ reaction, the substrate binds to the active site. In most cases, the substrate is held in the active site by weak interaction, such as H bonds and ionic bonds.
nonprotein helper for catalytic reactions; may be bound tightly to the enzyme or may bind loosely and reversibly with substrate; some are inorganic (metal atoms) and some are organic (coenzyme or vitamins)
reduce the activity of enzymes by blocking substrates from entering active sites
impede enzymatic reactions by binding to another part of the enzyme, which causes the enzyme to change molecule to change it shape. It renders the active site less effective at catalyzing the reaction
this occurs when a molecule bonds to some other location on an enzyme, causing a conformational change, which blocks the active site; after the molecule leaves, however, the enzyme returns to its original shape; may result in either inhibition or enhanced activity of an enzyme
Allosteric enzymes control the rates of key reactions in _______,. If ATP lags, then ADP accumulates and activates the key enzymes that speed up catabolism. If ATP is excessive, then catabolism slows down as ATP molecules accumulate and bind those same enzymes, inhibiting them.
a product of the metabolic pathway that acts as an inhibitor to block metabolic reactions
specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds
a chemical process that lyses or splits molecules by the addition of water; an essential process in digestion
adenosine triphosphate; triphosphorylated nucleotide that is used as a major energy source by the cell
The last phosphate bond in ___ is a high-energy bond, meaning that when the bond is broken, energy is released.
___ = A - P - P ∼ P (∼ means a high energy bond). It consists of three phosphate groups, ribose, and adenine.
ATP (adenosine triphosphate)
ATP is composed of the sugar ribose that has an adenine base and three phosphate groups. The adenine group is connected to the ___ carbon and the three phosphate group to the ___ carbon.
Energy is released from the ___ of ATP. It can be coupled to endergonic reaction in the form of phosphorylated intermediates.
The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by phosphorylation; addition of a phosphate group to a molecule
What are three ways of work that ATP can be used in a cell?
transport - help run a pump on a protein; mechanical - shape changes; chemical - ATP -> ADP
___ are responsible for catalyzing the reaction that couples ATP currency with cell reactions.
By coupling an endergonic reaction to ATP, hydrolysis, a suplus of energy is provided, making the entire process exergonic and thus able to proceed ____.
A ___ reaction takes place when the energy released from one reaction is used to fuel another.
____ involves capturing the energy stored in the bonds in glucose and storing that energy in the form of ATP
Discuss what happens to pyruvate in the presence and absence of oxygen.
Presence of O2 - the pyruvate generated by glycosis is metabolized to water and CO2; Absence of O2 - the pyruvate will undergo fermentation.
the removal of energy from glucose; common to all cells; enzymes mediate the breakdown of glucose
glucose (C6H12O6)-> pyruvate (2)3C; energy is released from the breakdown; first step of respiration
During glycosis, how many ATP are invested and how many are produced?
2 ATP are invested and 4 ATP are produced
If a pyruvate has oxygen available (aerobic), what is the process called?
cellular respiration (ATP will be broken down)
If a pyruvate does not have oxygen available (anaerobic), what is the process called?
fermentation (lactate or alcohol)
The ultimate goal of __________ is the transfer of energy stored within the bonds of large complex molecules to a more usable form, ATP.
What is the process of cellular respiration?
Carbohydrates are broken down with the consumption of oxygen to produce CO2, H2O, and energy (ATP + heat).
Red blood cells of mammal do not have mitochondria. Since RBC lack mitochondria and aerobic respiration takes place in mitochondria, what process provides their energy?
glycosis as the RBC undergoes anaerobic metabolism (fermentation does not provide energy).
What is the net production of ATP molecules from cellular respiration?
38 - glycolysis produces 4 and uses 2, Aerobic respiration produces about 36 molecules, thus the total is 38
Does oxidation and reduction always happen simultaneously?
yes, when something loses electrons something else always gains them.
Why is it called reduction when electrons are being gained?
when a molecule gains electrons, ti becomes more negative, thus its charge is reduced.
___ has a high electronegativity, so it's more likely to take electrons away from something else.
Why is energy a product of redox reaction?
Electrons have gone from a state of: 1) low electronegativity --> high electronegativity, 2) low attraction --> high attraction, 3) high potential --> low potential energy. Energy is released from each on of these
___ is a product of redox reactions when electrons go from a state of low electronegativity (high PE) to a state of high electronegativity (low PE).
During a ___ reaction, electrons are passed from the molecule, which is oxidized to the molecule, which is reduced.
In a redox reaction, a molecule that ___ another is itself oxidized as it loses electrons.
Oxidation and reduction always takes place together. In redox reactions, the molecule that gets reduced is called the ____ agent, while the molecule that gets oxidized is called the ___ agent.
In this equation, which molecule is being reduced? B + NAD+ --> C + NADH + H+
NAD+ is being reduced because it receives two electrons and a proton from B and oxidizes it to C
What are the key pathways from respiration?
1. glycolysis, 2. citric acid cycle, 3. oxidative phosphorylation, electron transport, chemiosmosis
In eukaryotic cells, ___ house most of the metabolic equipment for cellular respiration.
Glucose (C6H12O6) + 6O2 → 6CO2 + 6H2O + energy (ATP + heat). This is cellular respiration. What is the activation energy?
Glucose (C6H12O6) + 6O2 → 6CO2 + 6H2O + energy (ATP + heat). This is cellular respiration. What is being oxidized?
glucose to 6CO2
Glucose (C6H12O6) + 6O2 → 6CO2 + 6H2O + energy (ATP + heat). This is cellular respiration. What is being reduced?
6O2 to 6H2O
Glucose (C6H12O6) + 6O2 → 6CO2 + 6H2O + energy (ATP + heat). This is cellular respiration. Is this an exergonic reaction?
Because ___ is so electronegative, it is one of the most potent of all oxidizing agent (accepts).
What happens at each key step of cellular respiration?
electrons are stripped; each electron travels with a proton (H); NAD+ is a coenzyme, an electron acceptor, and functions as oxidizing agent during respiration
How does NAD+ trap electrons?
enzyme called dehyrogenases remove a pair of H atoms (1 e and 1 p) from a substrate, which oxidizes It; the dehydrogenases delivers 2 e along with one proton to its coenzyme, NAD+, the other proton is released as an H+ into the surrounding solution; by receiving 2 e but only 1 p, NAD+ has its charge neutralized when reduced to NADH; NAD+ is the most versatile acceptor in cellular respiration and functions in several redox steps in the breakdown of sugar.
Each NADH molecule formed during respiration represents stored energy that can be tapped to make ATP when electrons complete their "fall" down and ________ from NADH to O2.
How do electrons that are extracted from food and stored by NADH finally reach O2?
The H that reacts with O2 is derived from organic molecules, respiration uses an electron transport chain to break to fall of electron chain to break the fall of e into several energy releasing steps
Describe the electron transport chain.
the transport chain consists of a # of molecules, mostly proteins built into the inner membrane of a mitochondrion. Electrons removed from food are shuttle d by NADH to the top higher-dnergy end of the chain. At the bottom lower energy end, oxygen captures these e along with H nuclei forming water
Food -> NADH -> electron transport chain -> Oxygen. Is this endergonic or exergonic?
occurs in the cytosol, begins the degradation process by breaking glucose into two molecules of a compound called pyruvate
Citric Acid Cycle
takes place with in the mitochondrial matrix, complete the breakdown of glucose by oxidizing a derivative of pyruvate to CO2.
Some of the steps of glycosis and the citric acid cycle are _____ , in which dehydrogenase enzymes transfer electrons from substrates to NAD+ forming NADH.
The ___ accepts electrons from the breakdown products of the 1st two stages (most often via NADH) and passes these electrons from one molecule to another. At the end of the chain, the e are combined with O2 and H+ forming water. The energy released at each step of the chain is stored in a form the mitochondrion can use to make ATP.
electron transport chain
During the electron transport chain, ATP synthesis is called _________ because it is powered by the redox reactions of the electron transport chain.
What part of the mitochondrion is the site of electron transport and chemiosmosis, the process that together constitutes oxidative phosphorylation.
small amount of ATP is formed directly in a few reaction of glycosis and the citric acid cycle. This ode of ATP synthesis occurs when an enzyme transfers a phosphate group from a substrate molecule to ADP rather than adding an inorganic phosphate to ADP as is oxidative phosphorylation.
What step in cellular respiration can occur without oxygen, which is called fermentation. With oxygen the process is called respiration.
___ harvests chemical energy by oxidizing glucose to pyruvate; means "splitting of sugar"; glucose is a 6 carbon sugar and it broken down in to 2 each 3 carbon sugars called pyruvate
Which step in cellular respiration is called the energy investment phase as the cell spends ATP; however the investment is repaid with dividends when AtP is produced by substrate-level phosphorylation and NAD+ is reduced to NADH by electrons released from the oxidation of the food (glucose)? The net energy yield is 2 ATP plus 2 NADH
Glycosis releases less than 1/4 of the chemical energy stored in glucose; most of the energy remain stockpiled in the two molecules of ___.
If molecular oxygen is present, the pyruvate enters the mitochondrion, where the enzymes of the _________ complete the oxidation of the organic fuel.
citric acid cycle
___ enters the mitochondrion via active transport because it is a charged particle, then is converted to a compound called acetyl coenzyme A. CO2 diffuses out of the cell.
Which parts of cellular respiration that does not require oxygen?
glycosis and the citric acid cycle
Most of the ATP output of respiration is generated during _______, when NADH and FADH2 produced by the citric acid cycle relay the electrons extracted from food to the electron transport chain. In the process, they supply the necessary energy for the phosphorylation of ADP to ATP.
In which molecules is most of the energy from the citric acid cycle's redox reaction conserved? How will these molecules convert their energy to a form that can be used to make ATP?
NAHD and FADH2; they will donate e- to the electron transport chain
What cellular processes produce the carbon dioxide that your exhale?
CO2 is removed from pyruvate, which is produced by glycosis, and CO2 is produced by the citric acid cycle.
The metabolic components of glycosis and the citric acid cycle produce only ___ ATP molecules per glucose molecule, all by substrate-level phosphorylation.
4; 2 net from glycosis and 2 from the citric acid cycle
What are the electron escorts that link glycosis and the citric acid cycle to oxidative phosphorylation, which uses energy released by the electron transport chain to power ATP synthesis?
NAHD and FADH2
The pathway of electron transport, the electron transport chain, is a collection of molecules embedded in the ______ of the mitochondrion. The folding of the ______to from cristae increases the surface area, providing space for 1000's of copies of the chain in each membrane. Most of the components of the chains are proteins.
inner membrane; inner membrane
____ removed from food by NAD+ during glycosis and citric acid cycle are transferred from NADH to the first molecule of the electron transport chain, which is added during complex I of the chain.
Electrons are added at complex II of the chain from _____, which is a lower energy level than NADH does. Consequently, the electron transport chain provides about 1/2 less energy for ATP synthesis when the electron donor is ____ rather than NADH.
The electron transport chain makes no ATP directly. Its function is to ease the fall of electrons from food to ____, breaking a large free-energy drop into a series of smaller steps that release energy in manageable amounts.
How does the mitochondrion couple the electron transport and energy release to ATP synthesis?
An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP. Most ATP synthesis in cells occurs by chemiosmosis.
Example of chemiosmosis by chloroplasts
Chloroplasts use chemiosmosis to generate ATP during photosynthesis; in these organelles, light (rather than chemical energy) drives both electron flow down an electron transport chain and the resulting H+ gradient formation
Example of chemiosmosis by prokaryotes
Prokaryotes, which lack mitochondria and chloroplasts, generate H+ gradients against their plasma membranes. They then tap the proton-motive force not only to make ATP but also to pump nutrients and wastes across the membrane and to rotate their flagella
During respiration, how does most energy flow?
glucose -> NADH -> electron transport chain -> proton-motive force -> ATP
The three main departments of cellular respiration are glycosis, the citric acid cycle, and the electron transport chain, which drives __________.
What effect would an absence of O2 have on the process of electron transport chain and chemiosmosis (oxidative phosphorylation)?
Oxidative phosphorylation would stop entirely, resulting in no ATP production. Without oxygen to pull electrons down the electron transport chain, H= would not be pumped into the mitochondrion's inner membrane space and chemiosmosis would not occur.
In the absence of O2, what do you think would happen if you decreased the pH of the inner membrane space of the mitochondrion?
Because of the addition to H+ (decreasing the pH) would establish a proton gradient even without the function of the electron transport chain, we would expect ATP synthesis to function and synthesis ATP.
Remember: ____ refers to the loss of e- to any electron acceptor, not just oxygen. Glycosis oxidizes glucose to two molecules of pyruvate. The oxidizing agent of glycosis is NAD+, not oxygen, overall glycosis is exergonic, and some of the energy made available is used to produce 2 ATP by substrate-level phosphorylation. Glycosis generates 2 ATP whether oxygen is present or not.
_______ is an extension of glycosis that can generate ATP solely by substrate-level phosphorylation, as long as their is a sufficient supply of NAD+ to accept e- during the oxidation step of glycosis. NAD+ is recycled productively from NADH by the transfer of e- to the electron transport chain.
What are some types of fermentation?
1) alcohol fermentation in which pyruvate is converted to ethanol (yeast), 2) lactic acid in which pyruvate is reduced to form lactate with no release or CO2 (dairy products), 3) and in the human muscle cells by lactic acid fermentation
What are some similarities between fermentation and cellular respiration?
both use glycosis to oxidize glucose to pyruvate with a net production of 2 ATP by substrate-level phosphorylation; NAD+ is the oxidizing agent that accepts e- from food during glycosis
What are some differences between fermentation and cellular respiration?
fermentation - final electron acceptor is an organic molecule such as pyruvate; respiration - final electron acceptor is oxygen and harvests much more energy from a sugar molecule
Ancient prokaryotes probably used ___ to make ATP long before oxygen was present in Earth's atmosphere. This process does not require oxygen.
Consider the NADH formed during glycosis. What is the final acceptor for its e- during fermentation? Respiration?
Fermentation - a derivative of pyruvate, either acetaldehyde during alcohol fermentation or pyruvate itself during lactic acid fermentation; respiration - oxygen
A glucose-fed yeast cell is moved from an aerobic environment to an anaerobic one. For the cell to continue generating ATP at the same rate, how would its rate of glucose consumption need to change?
it would need to consume glucose at a much faster rate (19x more)
Glycolysis can break down other molecules besides glucose that we obtain from our foods. What are some examples?
Proteins can be broken down into amino acids; carbohydrates can be broken down into sugars; fats can be broken down into glycerol and fatty acids
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the ____ across the inner mitochondrial membrane.
H+ concentration gradient
In mitochondria, exergonic redox reactions provide the energy to establish the _____.
proton gradient (H+)
The final e- acceptor of the electron transport chain that function in oxidative phosphorylation is ___.
When e- flows along the electron transport chains of mitochondria, the ___ of the matrix increases.
organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer
Ruben and Kamen
Used an isotope of oxygen to prove Van Niel correct; that oxygen came from the breakdown of water, not CO2
___ is split during photosynthesis, providing the electrons needed to produce carbohydrates. It provides the source of electrons in the formation of carbohydrate from CO2 during photosynthesis.
What happens when water containing an oxygen isotope is supplied to a plant?
the oxygen isotope is released into the air
1st person to isolate and experiment with chloroplasts; light reaction -> split water and light independent reaction -> generate glucose
What coenzyme is the electron acceptor in photosynthesis?
NADP (Nicotinamide Adenine Dinucleotide Phosphate)
Light-___ reactions take in water and produce oxygen to make ATP and NADPH. Water is split is this reaction.
Light-___ reaction involves the uptake of CO2 to make carbohydrates. Carbon fixation happens in this reactions.
the process by which plants turn inorganic carbon (carbon dioxide) into organic compounds such as carbohydrates
During photosynthesis, water is oxidized and oxygen is reduced. Water is oxidized to form oxygen gas and CO2 is reduced to form ___.
During the general process of photosynthesis, the energy from light is used to accomplish the oxidation of water. Water is split to form oxygen gas in the light ____ reactions.
Small openings on the underside of a leaf through which oxygen and carbon dioxide can move and that permit evaporation of water. They are open during the day for photosynthesis and closed at night.
What part of the leaf can open and close, often found on the underside of the leaf, and are small pores composed of two guard cells?
CO2 is taken in and H20 vapor and O2 are released through the ___ and functions in the exchange of gases between a plant and its environment.
The cuticle is a waxy, waterproof covering that is secreted by the _____, which is the layer of cells on the upper surface of the leaf.
The fluid of the chloroplast surrounding the granum; involved in the synthesis of organic molecules from carbon dioxide and water.
A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.
green pigment in plants that absorbs light energy used to carry out photosynthesis; it is the light energy absorbed by chlorophyll that drives the synthesis of organic molecules in the chloroplast
What makes up a thylakoid?
bi-lipid membrane, proteins in groups that allows plants to use light for energy with are called light harvesting antennae, chlorphyll
Proteins are concentrated in certain areas of the membrane of the thylakoids. They are part of a system of proteins that move electrons. On of these proteins is called the "light harvesting antenna." These contain ___.
Chlorophyll contains a _____ ring that has a HC tail attached. Magnesium (Mg) is found in the center of it.
What structure is found within the thylakoid membrane?
a light harvesting antennae (contains chlorophyll)
Thylakoids are membrane enclosed sacks embedded with ____ and light harvesting antennae containing ___.
Why do leaves change color in the fall?
The plants stop making chlorophyll in the fall, which allows pigments other than green to be revealed.
Different colors of light have different wavelengths, which have different amounts of energy. Which colors have the highest rate of photosynthesis? lowest?
red and blue; green
Why is chlorophyll green?
green has the lowest rate of photosynthesis (less absorption of photons), and when you see a color it is because it reflects that color, not absorbing it. In other words, low absorption of green means a low rate of photosynthesis.
There are different types of chlorophyll that absorbs different colors, which makes photosynthesis more efficient. What are the types?
chlorophyll a (blue-green), chlorophyll b (yellow-gren), carotenoids (yellow-orange)
have an orange pigment, which explains the fall pigments; they absorb wavelength color of red and orange that chlorophyll can not
Leaves appear green to us because green light is largely ___. Chlorophyll, a major pigment in leaves, does not absorb green wave lengths of light effectively.
Both blue and red areas of the spectrum are the most effective for photosynthesis. Nearly all wavelengths of light are used for photosynthesis because of the presence of _______. Chlorophyll a has 2 peaks of read and blue in the spectrum.
True/False: Light has wave characteristics and particle characteristics.
True - light can bend like a wave and can become excited like a particle
What happens when a photon hits an electron? This is called photoelectric effect or photo-excitation.
the electron moves from a stable position to an unstable one
the energizing of e- from their ground state to higher orbitals in the absorption of light as energy; an electron gains energy when hit by a photon
Chlorophyll glows ___ when it's hit with UV light because energy is released from an electron that falls to is ground state.
red - because as it is hit with UV it's electron was excited to a higher energy level by UV light and as it falls back down to ground state, it emits light energy
Explain what happens when a photon hits and electron.
A photon, carrying lots of energy, travels at the speed of light toward the e-. The photon is much smaller and when it strikes, the e- becomes excited and gains energy when excited. The farther an e- is moved from the nucleus, the more unstable it is. It stays in excited state shortly and fall back to ground state. When it does this, a photon is released.
Chlorophyll ___ is the only chlorophyll molecule that has the atomic configuration to pass the e- on to a receiver.
A chlorophyll a electron can move to an excited state directly by light or indirectly by the transfer of energy from another ____.
Through heat loss and fluorescence, the electron returns to _____ state. The energy released is used to pump H to reduce coenzymes.
What are these characteristics of? 1) When it is excited by light it loses a high-energy electron, 2) one component is Mg, 3) it has a fatty acid tail, 4) it is able to act as a reducing agent
The ____ are groups of pigments that help capture energy from light in a photosystem.
light harvesting antennae
Photosynthetic ___ lack chloroplasts, but they do have photosynthetic membranes arising from in-folded regions of the plasma membrane that function in a manner similar to the thylakoid membranes of chloroplasts.
Summarize energy during respiration.
Energy is released from sugar when e- associated with H are transported by carriers to O forming water as a by-product. The e- lose PE as they "fall" down the e- transport chain toward electronegative O, and the mitochondrion harness that energy to synthesize ATP.
Summarize energy during photosynthesis.
Photosynthesis reverses the direction of water flow. Water is split, e- are transferred along with H+ from H2O to CO2, reducing it to sugar. Because the e- increases in PE as they move from H2O to sugar, this process requires energy. Th energy boost is provided by light.
What are the two stages of photosynthesis?
light reactions ("photo") and the calvin cycle ("synthesis")
Describe the light reactions.
Occurs in thylakoids; convert solar energy to chemical energy; Light absorbed by chlorophyll drives a transfer of e- from H2O to an acceptor celled NADP+, which temporarily stored the e-. H2O is split and gives off O2. The solar power reduces NADP+ to NADPH by adding H+. ATP is also generated using chemiosmosis to power addition of a Phosphate group ADP (phosphorylation). This light energy is converted to chemical energy in the compounds: NADPH (source of energized e-) and ATP (energy currency of the cell). No sugar is produced.
Describe the calvin cycle.
Occurs in stroma; Incorporates CO2 from air into organic molecules already present in the chloroplast (carbon fixation). The fixed carbon is then reduced to carbohydrate by the addition of e-. The reducing power is provided by NADPH (source of energized e). The ATP (chemical energy) converts CO2 to carbohydrates. Sugar is made with help of NADPH and ATP produced by light reactions. Mostly occus during daylight because it is waiting on the NADPH and ATP from light reactions.
How do the reactant molecules of photosynthesis reach the chloroplast in leaves?
CO2 enters leaves via stomata; H2O enters through roots and travels up veins
Hw id the use of oxygen isotope help elucidate the chemistry of photosynthesis?
the heavy element was tracked to prove oxygen came from H2O and not CO2 (Van Neil)
Describe how the two stages of photosynthesis are dependent on each other.
The calvin cycle depends on the NADPH and ATP that light reaction generates. Light reactions depend on NADP+ and ADP (+) P that the calvin cycle generates.
Chloroplasts are chemical factories powered by the sun. Their thylakoids transform light energy into the chemical energy of ___ and ___.
ATP and NADPH
Distances between the crest of each electromagnetic wave is called ___. The entire range of radiation is called the electromagnetic spectrum. The shorter the wavelength, the greater the energy.
The span of the electromagnetic spectrum most important to life is the narrow band from about 380 nm to 75 nm in wavelength. This is known as ___.
Light is a form of energy knows as electromagnetic energy or electromagnetic radiation. Electromagnetic energy travels is ___. Electromagnetic waves are disturbances of electric and magnetic fields rather than disturbances of a material medium such as water.
The sun radiates the full spectrum of electromagnetic energy, but the atmosphere only allows visible light to ass through while filtering out a substantial fraction of other radiation. ___ drives photosynthesis.
Substances that absorb visible light are known as ___, and different ones absorb different wavelengths.
The ability for a pigment to absorb various wavelengths of light can be measured with a ___.
We see green when we look at a leaf because ___ absorbs violet-blue and red while reflecting green light.
When a molecule absorbs a photon of light, one of the molecules e- is elevated to an orbital where it has more ____.
potential energy (normal orbital is ground state, orbital of higher energy is excited state)
The only ___ absorbed are those whose energy is exactly equal to the energy difference between the ground state and an excited state, and this energy difference varies. So, a particular compound absorbs only ___ corresponding to specific wavelengths, which is why each pigment has a unique absorption spectrum.
Once absorption of a photon raises an e- from the ground sate to an excited state, the e- can not remain there long and is unstable. When the e- falls back down, the energy is released as heat. As excited e- fall back down to the ground state, photons are given off. This afterglow is called ___.
Picture of photosystem in the interior of a thylakoid.
1) Energy of photon hits pigment, 2) transfer of energy to special chlorophyll a, 3) primary e- acceptor catches it (redox), 4) isolated chlorophyll fluorescences because there is no e- acceptor, so e- drops backdown to ground state, 6) the captured light energy to chemical energy will ultimately be used from synthesis of sugar.
The thylakoid has two types of photosystems. Describe them.
1) photosystem II (PSII) - functions 1st, reaction center is P680 because the pigment is best absorbing light at wavelength of 680 nm in red part of spectrum; 2) photosystem I (PSI) - functions 2nd, reaction center is called P700 because it is most effectively absorbing light with at wavelength of 700 nm.
The P680 and P700 are identical chlorophyll a molecules but their association with different proteins in the thylakoid membranes affects the e- distribution in chlorophyll molecules and accounts for different _____.
light absorbing properties
Light drives the synthesis of NADPH and ATP by energizing the two photosystems embedded in the _____ of chloroplasts.
Non-cyclic electron flow
produces ATP and NADPH is equal amounts; predominant route; the light reactions use solar power to generate ATP and NADPH, which provide chemical energy and reducing power to the sugar making reaction of the calvin cycle (P680)
Cyclic electron flow
The e- cycle back from ferredoxin (fd) to the cytochrome complex and from there continue to a P700 chlorophyll in the PSI reaction center. There is NO production of NADPH and no release of O2. Cyclic flow does generate ATP. Consumes more ATP that NADPH. Cyclic flow makes up the difference since it produces ATP by not NADPH.
energy coupling mechanism that uses energy stored in the for of H+ gradient across a membrane to drive work, such as synthesis of ATP. Most ATP synthesis in cells occur by chemiosmosis.
Comparison of chemiosmosis in chloroplasts and mitochondria. Describe.
chloroplasts and mitochondria generate ATP in the same basic mechanism: chemiosmosis. An e- transport chain assembled in a membrane pumps protons (H+) across the membrane as e- are passed through a series of carriers that are progressively more electronegative (redox). Mitochondria transfer chemical energy from food molecules to ATP and NADH. Chloroplasts transform light energy into chemical energy in ATP and NADPH. (Both pump from region of low to high)
Summary of light reactions.
Noncyclic e- flow pushes e- from water, where there are at a low sate of PE, to NADPH, where they are stored at a hight state of PE; the light driven e- current also generates ATP. Thus, the equipment of the thylakoid membrane converts light energy to chemical energy stored in NADPH to ATP. O2 is a by-product.
What color of light is least effective in driving photosynthesis? Why?
green because is is mostly transmitted and reflected, not absorbed by photosynthetic pigments
Compared to a solution of isolated chlorophyll, why do intact chloroplasts release heat and fluorescence when illuminated?
In chloroplasts, light excited e- are trapped by a primary electron acceptor, which prevents them from dropping them back down to the ground state. In isolated chlorophyll, there is not e-acceptor, so the photo-excited e- immediately drop back down to the ground state, with the emission of light and heat.
In the light reaction, what is the electron donor? Where does the e- end up?
Water is the e- donor (water is split); NADP+ accepts e- at the end of the e- transport chain, becoming reduced to NADPH.
The calvin cycle spends ATP as and energy source and consumes ___ as reducing power for adding high-energy e- to make the sugar. THE SUGAR IS NOT GLUCOSE, it is a 3 carbon sugar called G3P (glyceraldehyde-3 phosphate.
Describe the carbon fixation phase of the calvin cycle.
Each CO2 molecule is incorporated one molecule at a time. As CO2 enters the cycle a 5 carbon sugar, ribulose biphosphate, is attached. The enzyme that catalyzes the 1st step is ribuloe caroboxylase (Rubisco is the most abundant protein in chloroplasts and probably Earth). The product is a 6 carbon intermediate that immediately splits in 1/2 forming two molecules of 3-phosphoglycerate for each CO2.
Describe the reduction phase of the calvin cycle.
Each molecule of receives an additional phosphate group from ATP, becoming 1 ea 3-biphosphoglycerate. Next, a pair of e- donated from NADPH reduces 1 ea 3-biphosphoglycerate to G3P. For every 3 molecules of CO2 there are three G3P. Out of the 6G3P, only one exits.
Describe the regeneration phase of the calvin cycle.
Regeneration of the CO2 acceptor CRuBP aka ribose biphosphate; the 5 ea G3P left in the phase II are rearranged into 3 molecules of RuBP. To accomplish this, the cycle spends three more molecules of ATP. The RuBP is now prepared to receive CO2 again and the cycle continues.
What does the calvin cycle consume to net synthesis one G3P molecule?
9 molecules of ATP and 6 molecules of NADPH
The ___ that is spun off become the starting material for metabolic pathways that synthesis other organic compounds.
To synthesis one glucose molecule, the calvin cycle uses ___ molecules of CO2, ___ molecules of ATP, and ___ molecules of NADPH.
6 molecules of CO2, 18 molecules of ATP, 12 molecules of NADPH
Explain why the high number of ATP and NADPH molecules used during the calvin cycle is consistent with the high value of glucose as an energy source.
The more PE that a molecule stores, the more energy and reducing power required for the formation of that molecule. Glucose is available energy source because it is highly reduced, storing lost of PE in tis electrons to reduce CO2 to glucose, much energy and reducing power are needed in the form of a high number of ATP and NADPH molecules.
Provide a brief summary of Photosynthesis.
Light reactions capture solar energy and use it to make ATP and transfer e- from water to NADP+. The calvin cycle, uses the ATP and NADPH to produce sugar from CO2. The energy that enters the chloroplasts as sunlight becomes stored as chemical energy in organic compounds.
Does the following happen in the light reaction or calvin cycle of photosynthesis? 1) carried out by molecules in the thylakoid membrane, 2) convert light energy to the chemical energy of ATP and NADPH, 3) split water and release O2 to the atmosphere, 4) light dependent
light reactions (PSI and PSII)
Does the following happen in the light reaction or calvin cycle of photosynthesis? 1) take place in stroma, 2) use ATP and NADPH to convert CO2 to the sugar G3P, 3) return ADP, inorganic phosphate, and NADP+ to the light reactions, 4) make glucose, 5) light independent
____ occurs in mitochondria, uses glucose, releases CO2 and uses O2, NADH is carrier molecule, goes through the cycle first then the electron transport chain.
___ occurs inside chloroplasts, goes through the electron transport chain first, releases O2 and uses CO2, uses NADPH.
What is the difference of cyclic and noncyclic electron flow?
only cyclic electron from can operate in the absence of PSII
What is the difference of autotrophs and heterotrophs?
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2, and other nutrients that are inorganic
Where do the following processes occur: carbon fixation, oxidation of NADPH, regeneration of the CO2 acceptor, consumption of ATP?
What are the two stages of photosynthesis?
1) light reaction - water is split in the grana releasing O2, producing ATP, and forming NADPH, 2) calvin cycle - sugar forms in the stroma from CO2 using ATP for energy and NADPH for reducing power
What does this energy flow represent: glucose -> NADH -> electron transport chain -> proton motive force -> ATP?
Cyclic electron flow
route of electron flow during the light reactions of photosynthesis that involves only PSI and produces ATP but not NADPH or O2
Non cyclic electron flow
route of electron flow during light reactions of photosynthesis and produces ATP, NADPH, and O2; the net e- flow is from water to NADP+
fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from CO2 to H2O
How is DNA packed?
2 strands of DNA -> DNA wrapped around proteins (chromatin) -> 2 molecules of DNA (chromosome)
What phase of mitosis takes up 90% of a cells's life and accounts for when most proteins are formed?
interphase (90% interphase, 10% mitosis)
What occurs in the G1 (Gap 1) phase of interphase?
cell functions; protein supply increases; cell grows in size
What occurs in the G2 (Gap 2) phase of interphase?
the cell grows some more in preparation for division
If a cell is in a state in which it no longer divides then the cell is probably arrested at which stage of the cell cycle?
Identifiable chromosomes are present in the cell only during the ___ phase, during cell division.
What occurs in M (mitosis) phase?
nucleus splits and chromosomes form - remember that DNA is only packed into chromosomes when a cell is going to do mitosis
Where is the kinetochore located on a chromosome?
part of the centromere that connects to the spindle fibers (microtubules)
What are three types of chromosomes?
acrocentric (in between midpoint and end), metacentric (middle), telocentric (end)
How is a chromosome split?
spindle fibers move chromosomes; spindle fibers are made of tubulin subunits (microtubules) that connect to the center of the chromosome and pull it apart
At the end of G2, the ____ breaks down and uses the material from the mircrotubules to make spindle fibers.
What does this describe: chromatin consists of DNA with associated proteins, DNA condenses during M in the life cycle of the cell, replicated chromosomes consists of two chromatids that are identical?
A cell containing 12 replicated chromosomes at the beginning of mitosis will have how may chromosomes after the completion of mitosis?
___ is best described as a division of the nucleus, in which two daughter nuclei are formed that are identical to that of the parent cell.
The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, chromatin exists as a mass of very long, thin fibers that are not visible with a light microscope.
one of the two strands that constitute a chromosome; chromatids are held together by the centromere
cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases; centriole and centrosome is doubled, cell grows, chromatin begin to coil to form chromosomes
Structure present in the cytoplasm of animal cells, important during cell division; functions as a microtubule-organizing center. A centrosome has two centrioles.
first and longest phase of mitosis; centrosomes start to separate; asters (microtubules) form; sister chromatids form and supercoil to form chromosomes
the second stage of mitosis, during which the nuclear envelope breaks down,the spindle microtubules attach to the kinetochores of the sister chromatids and cause chromosomes to move
the stage third in mitosis, in which the duplicate chromosomes line up along the equatorial plate of the spindle
The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell. The cell begin`s to elongate, spindle fibers begin to disassemble and shorten, and by the end of the phase the cell will have a full set of genetic information
last phase of mitosis, nuclear envelope and nucleolus start to reform, centrosomes begin to divide, cleavage furrow begins to form
If the haploid number of an organism is 5, then each dividing cell will have how may chromatids at miotic metapase?
haploid = 1 chromosome; diploid = 1 chromatid; 5 haploids = 10 diploids; chromosomes are duplicating in metaphase, so 10 x 2 = 20 diploids (chromatids)
If a cell with 3 pairs of homologous chromosomes undergoes cell division, how may chromatids will it have at metaphase of mitosis?
1 homologous chromosomes = 2 chromosomes (4 chromatids), so 3 homologous pairs x 4 chromatids = 12 chromatids
How do animal cells split?
Mircofilaments attach to each side of the membrane made up of actin, and myosis slide up and down the actin, which causes contractions and shortens the filaments. This causes the membrane to bend inwards until a cleavage furrow forms and is pinched in two.
Who does a plant cell split?
The Golgi makes new cell membranes and creates a chain of Golgi vesicles that migrate across microtubules to fuse with each other in the middle of the plant cell. Golgi is made of membrane and inside the vesicles are proteins and enzymes. The enzymes build a new cell wall.
If mitosis where to occur without cytokinesis what would be likely to happen?
there would be cells with several nuclei
What is the difference of cytokinesis in a plant cell and an animal cell?
animal cell - contractile ring forms which pinches the cell in tow; plant cell - Golgi vesicles fuse to form a new plasma membrane and the cell plate
all the DNA in one cell of an organism (prokaryote genome is one long strand of DNA; eukaryote genome is multiple DNA)
Starting with a fertilized egg (zygote), a series of 5 cell division would produce an early embryo with how many cells?
zygote = 1 cell
first step = 2 cells
second step = 4 cells
third step = 8 cells
fourth step = 16 cells
fifth step = 32 cells
A chicken has __ chromosomes in its somatic cells if the following is true: chicken inherited 39 chromosomes from each parent, the chicken has 39 chromosomes in each gamete, each offspring of the chicken has 78 chromosomes.
What are the phases of Interphase?
G1 (cell grows), S (grows more and copies chromosomes), G2 (grows more and completes preparations for cell division)
A spindle-shaped structure formed of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis and meiosis; forms in the cytoplasm during prophase and elongates by adding subunits of the protein tubulin; the assembly of the microtubules starts at the centrosome
material present in te cytoplasm of all eukaryotic cells, important during cell division, the microtubule organizing center; most plant cells lacks centrosomes
One of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope; play a role in cell division.
Each of the two chromosomes has a ____, a structure of proteins associated with specific sections of chromosomal DNA at the centromere. During prometaphase, some of the spindle microtubules attach to the kinetochores, which are called kinetochore microtubules.
A method of asexual reproduction by "division in half." In prokaryotes, binary fission does not involve mitosis; but in single-celled eukaryotes that undergo binary fission, mitosis is part of the process. Chromosomes double then split
reproduction that does not involve the union of gametes and in which a single parent produces offspring that are genetically identical to the parent (budding and binary fission)
English natural scientist who formulated a theory of evolution by natural selection (1809-1882); Wrote "The Origin of Species" and "The Descent of Man"; (Overpopulation, variation, competition, survival of the fittest, reproduction)
Individuals who recieve new combinations of genes from their parents; genetically different from their parents
Why doesn't mitosis work for sex cells?
because at fertilization, the chromosome number would be double that of a somatic cells and the organism would not survive
Yeast, a single celled fungi, ofter replicates by pinching off into two unequal sized cells. This process is called ___.
the two chromosomes in a chromosome pairs that have the same genetic composition and are derived from different parents
When do homologous chromosomes originate?
During fertilization, each parent contributes a haploid cell that has one of each chromosome. After fertilization, the resulting cell will have two of each chromosome.
Sister chromatids are attached at the ___. Homologous chromosomes have the same gene loci, but may have different alleles for those genes.
True/False: Homologous chromosomes have genes for the same traits.
True, but the alleles may be different
What purpose does meiosis serve in animal cells?
formation of gametes, reduction of chromosome number in half, formation of haploid germ cells, does not produce identical daughter cells
Occurs during prophase I; the side by side pairing of homologous chromosomes at the start of meiosis
a point of overlap of paired chromatids at which fusion and exchange of genetic material occurs during prophase I of meiosis
Crossing over can contribute to ___ by exchanging genetic material between non-sister chromatids of homologues (homologous pair)
Steps of Prophase I during meiosis
chromosomes condense, homologous chromosomes synapse and form tetrads, crossing over (chiasmata), kinetochores attach to microtubules and move to the middle
Steps of Metaphase I during meiosis
chromosome pairs line up, homologous chromosomes organize and line up as tetrads, still attached to microtubules (the kinetochores)
Steps of Anaphase I during meiosis
homologous pairs separate, sister chromatids remain attached as they move up the spindle towards opposite poles
Steps of Telophase I during meiosis
cleavage furrow forms and forms tow new cells, each with 1 chromosome from each homologous pair (haploid); then cytokenisis
Steps of Prophase II during meiosis
nuclear membrane breaks apart, spindle fibers form, start to move towards middle
Steps of Metaphase II during meiosis
non-homologous pairs line up in middle of metaphase plate; because of crossing over the two sister chromatids are not identical; kinetochores are attached to spindles
Steps of Telophase II during meiosis
nuclei form and chromosomes condense, cleavage furrow forms, 4 haploid cells are eventually produced, then cytokenisis, ready for sexual reproduction
error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes
What are the similarities of mitosis and meiosis?
DNA is replicated before both; consists of the phases prophase, metaphase, anaphase, and telophase
(Mitosis or Meiosis?) It conserves chromosomes because it replicates then divides once (diploid to diploid).
(Mitosis or Meiosis?) It reduces chromosomes because replicated then divides twice (diploid to haploid).
What are some differences in Mitosis and Meiosis?
function, synapsis happens only in meiosis, number of chromosomes in final product, metaphase (mitosis - single chromosomes line up, meiosis - homologous pairs line up)
The goal of ___ is to produce haploid gametes, each having one chromosomes from each chromosome pair.
What is the formula to find out how many possible combinations are in a trait?
2x = N
(x = # of pairs)
Homologous chromosomes randomly align at the metaphase plate during ___ (mitosis or meiosis)?
____ is the result of the random orientation of homologous pairs of chromosomes along the metaphase plate.
A type of cell within the seminiferous tubules that nurtures developing sperm and secretes hormones.
Picture of sperm
sperm have haploid nucleus, the acrosome carries enzymes to penetrate the egg, the mitochondrion provides fuel for the sperm
Sperm production occurs a couple of degrees below body temperature. This is why ___ hangs below the penis. It is to maintain a lower temperature.
At the base of the ___, where it attaches to the head of the sperm is mitochondria to provide energy for movement of the sperm.
T/F: The sperm functions to provide genetic material to the fertilized egg, but it does not contribute cytoplasm.
T/F: Meiosis is the division of a diploid cell (2n) to form haploid cells (n) called gametes.
is the process of meiosis that takes place in the ovaries of a female; forms one large egg cell and three polar bodies
T/F: The female cell does not go into meiosis II until fertilization. It will not occur unless fertilization takes place.
a cell that results from an unequal division of cytoplasm during oogenesis; they eventually degrade
Why are polar bodies produced during the female reproductive cycle?
Should fertilization occur, cytoplasm is conserved in the egg (ovum) cell to nourish a developing zygote
produce exact copies of themselves; a single individual is the sole parent and passes copies of its genes to its offspring
An individual that reproduces asexually gives rise to a ___, a group of genetically identical individuals.
two parents give rise to offspring that have unique combinations of genes inherited from two parents
How are traits of parents (such as hair color) transmitted to their offspring?
Parents pass genes to their offsprings that program cells to make specific enzymes and other proteins whose accumulative actions produce an individuals inherited traits.
Asexual organisms produce offspring that are genetical to each other. Why?
They reproduce by mitosis
If the content of a diploid cell in the G1 phase of the cell cycle is "x", then the DNA content of the same cell at metaphase of Meiosis I would be ___. At metaphase II of meiosis, it would be "x" (haploid).
How many different combination of maternal and paternal chromosomes can be packaged in gametes made by an organism with a diploid number of 8?
diploid # = n; 2n = x; 2*8 = 16
In comparing the typical life cycles of plants and animals, a stage found in plants but not in animals is a multicellular ___.
How does the karyotype of a human female differ from that of a human male?
a female has 2 X chromosomes; a male has an X and Y chromosome
Dog sperm contain 39 chromosomes. What are the haploid number and diploid number for dogs?
(n) haploid = 39; (2n) diploid = 78
What process (mitosis or meiosis) is more directly involved in the production of gametes in animals? plants? fungi?
animals = meiosis; plants = mitosis; fungi = mitosis
If the DNA content of a diploid cell in G1 phase of the cell cycle is X, then the DNA content of the same cell at metaphase of meiosis I would be ___.
2X because it has been replicated but not yet split
What 2 rules do Mendel's law of segregation and independent assortment follow?
rules of multiplication and rules of addition
The multiplicative law
the probability of two independent events co-occuring is the product of their individual probabilities; can be used to determine the probability that a given genotype will occur
A male has a recessive human disorder, what is the probability that a sperm he produces will carry the gene trait?
100% - according to the law of segregation, each gamete receives one of the 2 alleles for each trait from the parent. When a man has a recessive genetic disorder, he carries two alleles for the disorder.
Ex. of multiplicative rule: A father is carrier of a recessive genetic disorder. The mother is homozygous for the condition. What is the probability that their child will be a carrier?
1/2 * 2/2 = 2/4 = 50 %
Ex. of multiplicative rule: In humans there is an equal likelihood of producing males adn females. What is the probability of a couple producing 4 males?
xx (x) xy = 1/2
1\2 1\2 1\2 * 1\2 = 1\16 chance of having 4 males
The probability of two independent events occurring at the same time is the product of their individual probabilities.
The probability of one or another of two mutually exclusive (or separate) events occurring equals the sum of their individual properties.
Ex. of additive rule: What are the odds that the genotype of the offspring is Ss? Note: The additive and multiplicative rules are combined to solve genetic problems.
Male Ss (1\2 S x 1\2 s) = 1\4
Female Ss (1\2 S x 1\2 s) = 1\4
1\4 + 1\4 = 2\4 = 1\2 Ss
Ex of additive rule: What are the odds that the phenotype of the offspring will be round? S = round dominant, s = square recessive
Ss x Ss
Possible combinations of round: SS, Ss, sS
Ss (1\2 S x 1\2 s) = 1\4 Ss
sS (1\2 S x 1\2 s) = 1\4 sS
SS (1\2 S x 1\2 S) = 1\4 SS
1\4 + 1\4 + 1\4 = 3\4 round
Note: Additive and Multiplicative Rule
What are the odds that the phenotype of the offspring will be yellow and wrinkled? y=yellow, y=green, S=round, s=wrinlked
yYss = 1\2 y, 1\2 Y, 1\2 s, 1\2 s = 1\16
Yyss = 1\2 Y, 1\2 y, 1\2 s, 1\2 s = 1\16
YYss = 1\2 Y, 1\2 Y, 1\2 s, 1\2 s = 1\16
1\16 + 1\16 + 1\16 = 3\16 yellow wrinkled
the crossing of an individual of unknown genotype with a homozygous recessive individual to determine the unknown genotype
disease that results from a defect in the plasma membrane and causes complications of the lungs, pancreas, and sweat glands
diagram showing the gene combinations that might result from a genetic cross; Reginal Punnett (1905)
creates a blended phenotype; one allele is not completely dominant over the other
law of independent assortment
Mendelian principle stating that genes for different traits are inherited independently of each other; applies only to genes located on different chromosomes
production of offspring whose phenotypes differs from the parental phenotype; in the formation of gametes, genes for different traits are sorted randomly
An organism that is heterozygous for two independently segregating traits can produce how may different kinds of gametes?
organisms that are reproduced for a specific trait and always produce offspring that have the same phenotype for that trait; only produce one type of gamete
In pea plants, yellows seeds (Y) are dominant to green seeds (y) and smooth seeds (S) are dominant to wrinkled seeds (s). What do you put in the punnett square if the parents are YySs x YySs?
horizontal: YS, yS, Ys, ys
vertical: YS, yS, Ys, ys
What is the chance of a cross YySs x YYSS producing an offspring of genotype YYSs?
YY x Yy = 4\4 YY and 2\4 YY = 8\16 = 1\2
Ss x SS = 2\4 SS and 4\4 SS = 8\16 = 1\2
1\2 * 1\2 = 1\4 YYSS
the heterozygote has a unique phenotype which is intermediate to the two parental phenotypes; neither allele dominates
a condition in which both alleles for a gene are fully expressed; both contribute to the phenotype
an immune globulin produced by B cells which binds to antigens, and in doing so function in immune response.
Blood type A. What is the antigen present, genotypes, and antibody present?
Blood type A
Antigen present: Oᴬ
Genotype: IᴬIᴬ or Iᴬi
Anitbody present: Anti B
Blood type B. What is the antigen present, genotypes, and antibody present?
Blood type B
Antigen present: Oᴮ
Genotype: IᴮIᴮ or Iᴮi
Anitbody present: Anti A
Blood type AB. What is the antigen present, genotypes, and antibody present?
Blood type AB
Antigen present: Oᴬᴮ
Anitbody present: none
Note: Universal recipient
Blood type O. What is the antigen present, genotypes, and antibody present?
Blood type O
Antigen present: none
Anitbody present: Anti B and Anti A (Both)
Note: Universal donor
Why is a person with blood type AB considered the "universal recipient"?
they do not produce any antibodies and AB blood will not attack the A or B antigens because they do not have any antibodies
A man is Iᴬ and woman is Iᴬ. What is their chance of having a boy with O blood type?
Boy = 1\2 or 50%
II or O blood type = 1\4 or 25%
1\2 * 1\4 = 1\8 chance of having a boy with O blood type
What will occur if some one with IᴬIᴮ donated blood to ii?
If type AB were transfused into a person with O, the antiA and antiB antibodies in the recipients blood will attach the A and B antigens on the transfused blood
What are the two possible genotypes of a person who has B antibodies/
B antibodies = A Bood type = IᴬIᴬ and Iᴬ i
a diagram that shows the occurrence of a genetic trait in several generations of a family; used in population genetics to trace family histories (P = parental generation, F1 = 1st offspring, F2 = 2nd offspring, and so on.)
Explain codominance vs. incomplete dominance.
Incomplete dominance example:
RED Flower x WHITE Flower ---> PINK Flower
**two different phenotypes produces offspring with a third phenotype that is a blending of the parental traits.
red x white ---> red & white spotted
**different phenotypes produces offspring with a third phenotype in which both of the parental traits appear together.
trait is controlled by several allelic pairs each dominant allele contributes to the phenotype
norm of reaction
The range of phenotypes produced by a single genotype, due to environmental influences.
male; X carry most of all chromosomes; Y is important chromosome TDF (testicle developmental factor)
For sex-linked recessive traits, males are ___ and need only 1 allele to express the trait. Females will be homozygous and need 2 alleles to express the trait.
What are some examples of sex-linked recessive traits?
hemophilia, colorblindness, duchenne muscular dystrophy
in females with XX genotype, one X is inactivated after zygote formed during embryonic development; this explain why males survive with only 1 X chromosome
inactive X chromosome (condensed + visible) inside nuclear envelope- occurs randomly and independently in each embryotic cell that is present @ the time of X-inactivation; this explain why males survive with only 1 X chromosome
in biology, used to describe patchiness in a characteristic; example: calico cats, there is no such thing as calico male cats
How can unfavorable lyonization occur?
Both of these must happen: 1) a heterozygous female carries an allele of a series condition on X chromosome, 2) the functioning X chromosome becomes inactivated in most of the cells of the body and the defective one remains active with the disease . This is random.
What are evidences that supports lyons hypothesis?
1) presence of barr bodies in females, 2) all calico cats are females, 3) mosaic of sweat gland present in the ectoderm of some females. The lyon hypothesis seeks to explain how cells compensate for the difference in X chromosome number in females vs. males.
in the *heterozygote*, the allele that causes the disorder masks the dominant allele (ex: H=trait, h=normal)
a trait that is expressed in the *homozygous* condition (ex: h=trait, H=normal)
in males or females, one abnormal allele on the x chromosome causes the disorder (ex: Xᴴ=trait, Xʰ=normal)
males with one abnormal allele express the trait, only homozygous females show the trait (ex: Xʰ=trait, Xᴴ=normal)
Describe the pattern of inheritance of an autosomal dominant disorder.
Autosomal dominant disorder is expressed in the heterozygous and homozygous conditions and is coded for a non-sex chromosome.
Chromosome theory of inheritance
mendelian genes have specific loci on chromosomes, and it is the chromosomes that undergo segregation and independent assortment
The number of genes in a cell is far greater than the number of chromosomes. Each chromosome has 100's or 1000's of genes. Genes located on the same chromosome that tend to be inherited together in genetic crosses are called ____.
the production of offspring with combinations of traits differing from those found in either parent
meiosis in which there is a failure of paired homologous chromosomes to separate
EX. results in an abnormal number of chromosomes in the daughter cells
levels of chromatic packing
1) short region of DNA double helix, 2) beads on a string form of chromatin with histones, 3) section of chromosome in extended form, 4) condensed section of chromosome, 5) entire mitotic chromosome
The information content of DNA, the genetic material, is in the form of specific sequences of ___ along the DNA strands.
The organic process whereby the DNA sequence in a gene is copied into mRNA. The result is an mRNA strand.
EX. the process whereby a base sequence of messenger RNA is synthesized on a template of complementary DNA
The process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm. The result is a polypeptide strand, which is a precursor to a protein.
Why can't it go from DNA -> Protein?
1) it provides protection for the DNA and genetic information, 2) using RNA as an intermediate allows more copies of a protein to be made simultaneously, since many mRNA transcripts can be made from only on gene
Translation and transcription in prokaryotes.
In a cell lacking a nucleus, mRNA produced by transcription is immediately translated without additional processing
Translation and transcription in eukaryotes.
The nucleus provides a separate compartment for transcription. The original RNA transcript (pre-mRNA) is processed in various ways before leaving the nucleus as mRNA.
The flow of information from gene to protein is based on a ___. The genetic instructions for a polypeptide chain are written in the DNA as a series of non overlapping, three nucleotide words.
During transcription, the gene determines the sequence of bases along the length of an mRNA molecule. For each gene, only one of the two DNA strands is transcribed. This strand is called the ___ because it provides the template for ordering the sequence of nucleotides in an RNA transcript.
An mRNA molecule is complementary rather than identical to its DNA template because RNA bases are assembled on the template according to ______. It is also synthesized in an antiparallel direction to the template strand of DNA.
base pairing rules
The mRNA base triplets are called ___, and they are customarily written in the 5" -> 3" direction. Because codons are base triplets, the number of nucleotides making up a genetic message must be 3x the number of amino acids making up the protein product.
codons; EX: 300 nucleotides on mRNA = polypeptide that's 100 amino acids long
Levels of transcription to translation.
DNA molecule -> DNA molecule unwinds by an enzyme called polymerase -> mRNA transcribes the DNA strand in the 5' to 3' direction -> mRNA copies as codons -> the codons are translated into amino acids
a specific nucleotide sequence of DNA where RNA polymerase binds and initiates transcription
In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene.
The prometer sequence in DNA is said to be upstream from the terminator. The stretch of DNA that is transcribed into an RNA molecule is ____.
Describe initiation part of transcription.
After RNA polymerase binds to the promoter, the DNA strands unwind and the polymerase initiates RNA synthesis at the start point on the template strand.
Describe elongation part of transcription.
The polymerase moves downstream unwinding the DNA and elongating the RNA transcript, the RNA strands reform a double helix.
Describe termination part of transcription.
Eventually, the RNA transcript is released, and the polymerase detaches from the DNA.
transfer RNA (tRNA)
RNA that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA.
As mRNA is moved through a ___, codons are translated into amino acids, one by one. The interpreters are tRNA molecules, each with a special at one end of a corresponding amino acid at the other end. tRNA adds to amino acid group to a growing polypeptide chain when the anticodon bonds to complementary codon on the mRNA.
A chromosomal alteration in which the organism possesses more than two complete chromosome sets; most common in plants; plays a major part in speciation
technique in which an individual's metaphase I chromosomes are examined in order to determine their number and characteristics
A human genetic disease resulting from having an extra chromosome 21 (three chromosomes at number 21), characterized by mental retardation and heart and respiratory defects.
chromosomal aberration in which one or more chromosomes are present in extra copies or are deficient in number
a condition in a diploid cell in which one chromosome of one pair is missing as a result of nondisjunction during meiosis
A primary sex cell experiences one nondisjunction during meiosis I. If the normal diploid number is 46, how many chromosomes are present in one of the defective gametes?
nondisjunction is when chromosomes fail to separate;
23 + 1 = 24 chromosomes per gamete or
23 - 1 = 23 chromosomes per gamete
T/F: It is not uncommon for chromosomes to break and recombine, trading genes and losing some genetic information.
What are two alterations that can happen to chromosomes that ultimately change their structure?
deletion and crossover
Characteristics of homologous chromosomes.
1) nondisjunction occurs when they do not separate in cell division, 2) mistakes in crossover events between them cause duplication and inversion mutations, 3) they are shown in pairs in a karyotype
change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome; can be reciprocal and nonreciprocal
genetic material moves from one chromosome to another without any reciprocal exchange
2 nonhomologous chromosomes exchange parts, no genetic information is gained or lost, may cause nothing, cancer, or abnormal offspring
Crossing over occurs when homologous chromosomes exchange parts, and reciprocal translocation occurs when ______ chromosomes exchange parts.
A protein is made of a polypeptide strand, a chain of ____ joined by polypeptide bonds. DAN -> RNA -> amino acids -> Protein
Prokaryotic transcription and translation.
In bacteria transcription and translation are not segregated. mRNA is transcribed by the DNA strand and is then translated by ribosomes into a polypeptide. Both transcription and translation happens in the cell because it is not compartmentalized.
Eukaryotic transcription and translation.
Transcribes in the nucleus, DNA remains unchanged while mRNA makes a copy of DNA, translation occurs outside of the nucleus and translated mRNA into "the music of proteins", transcription and RNA processing happens in the nucleus and translation happens outside of the nucleus
series of DNA nucleotides (15-300 base pairs long) that serves as the site where RNA polymerase binds
In both prokaryotes and eukaryotes, RNA polymerase reads the template DNA in what direction when it lands on the TATA box and opens up?
reads 3' to 5' and adds 5' to 3'
What consists of a termination sequence in transcription?
A grouping oF A (adenine) and T (thymine) on the DNA strand because they are 2 ring Hydrogens; G and C are 3 ring H. If you have a lot of A and T then the 2 H bonds are weaker. The RNA Strand is lifter from the strand, snaps off, and DNA closes up.
How is the mRNA strand protected once it is done transcribing?
each end is capped; the 5' end is capped with methylated guanine triphosphate; 3' end is capped with Poly A tail
Poly A tail
consists of 200 nucleotides; attached to the 3' end of RNA; protects against degradation; helps export RNA from the nucleus
Methylated guanine triphosphate
attached to the 5' end of RNA; serves as a leader or signal for the beginning of translation; protects the RNA from degradation by enzymes
What molecules does RNA polymerase require assistance from?
transcription factors and promoter DNA sequences are necessary for RNA polymerase to transcribe a strand of DNA
In eukaryotes, during transcription ___ occurs between the DNA template and the mRNA strand.
The ___ protects the mRNA from degradation by hydrolytic enzymes and the ___ asists the mRNA in export from the nucleus.
5' cap; poly a tail
Review of mRNA.
carries the information needed to make proteins, it is exproted from the nucelus into the cytoplasm, it must be translated from nucleotide language to protein language (tRNA) to make polypeptides
synthesis of a polypeptide starnd using the genetic information present in the RNA molecule
its structure allows it to cary amino acids to the mRNA, it is syntehsized in teh nucleus and the twisted into a specific shape, attached to the 3" amino acid
One of three loops on a tRNA which contains the 3 nucleotides that allow it to align specifically with mRNA. Contains the anticodon
The organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus
Review ribosomal RNA (rRNA)
made in the nucleolus and synthesised along a DNA strand, the ribosome is an organelle comprised of protein and rRNA
What percentage of the ribosome is RNA and proteins?
60% RNA; 40% proteins, 2 subunits that bring the mRNA and tRNA together, which are complementary
The amino acid attaches to the tRNA at the 3' end. The amino acid attaches to the tRNA at the ___, opposite the anticodon loop.
How does the tRNA get a specific amino acid?
There are 20 different enzymes, each responsible for binding a specific amino acid to tRNA. tRNA recongnizes the mRNA and carries a specific amino acid. These enzymes are called tRNA synthatase or "transferase."
take the energy of an ATP bond and harness it to provide energy for an endergonic reaction; 2 phosphate bonds are broken converting ATP to AMP; must have energy, not spontaneous; key to energy transfer within the cell
How does an amino acid get bound to the proper tRNA?
There are 20 different enzymes each responsible for bringing a specific amino acid to tRNA, generally called transferase (actyl-tRAN synthease) that are specific to both one amino acid and one tRNA molecule.
The funcion of tRNA during protein sysnthesis is to bring the appropriate amino acid to the growing ____ strand during translation.
___ occur in prokaryotes and eukaryotes. They allow translation to occure along multiple points on the mRNA strand. Translation of the polyribosimes occurs in the 5' to 3' direction.
During translation, the first ribosome attaches to the 5' initiation sequence of the mRNA molecule. As the molecule moves in the __ direction, a new incoming ribosomes attaches to the 5" site.
How does a acell know if a protein will remian in the cytosol, become part of the ER, or be secreted out of the cell?
signal peptides, which are sequences of about 20 amino acids on polypeptides that target a protein to the ER. They are found in the beginning of a polypeptide chain
There is a single peptide that will attache and bond the the __, whcih snakes protein to it and eventually pumps protein into the rough ER.
Found in eukaryotic and prokaryotic cells, enable a cell to make many copies of a polypeptide very quickly during translation; multiple ribosomes attached to an MRNA strand
Review signal peptides.
a polypeptide is bound for secretion or the ER if it tagged with a signal peptide; the ribosomal complex moves to the rough ER and the signal peptide binds to a receptor protein; the polypeptide eventually moves to the ER system; polypeptides that remain in the cytosol don't have a signal peptide
T/F: A synthesis of a polypeptide is occuring in the cytosol. If this protein is destined for mitochondria, chloroplasts, or peroxisomes, the growing polypeptides strand continues to be synthesized in the cytosol.
Signal sequences on ___ usually are found only on the amino terminal end of the chain.
Translation - mRNA is made 5' to 3' and polyribosomes attach to mRMA, initiation begins with the start codon binding with the initiator tRNA at the P-site. The rest of the ribosomes are added with the E, P, and A-site. GTP provides the energy needed to form a peptide bond and the ribosome is ready to move down RNA, so the tRNA move into the E-site because it is done. It has lost the amino acid.
The lost amino acids will be bonded to the next tRNA in line and keeps the cycle going. Release factor binds to the stop codon and the peptide chain i broken off tRNA. Once the peptide is released it may stay in the cytosol, be tagged for the ER, or go to the nucleus.
In protein synthesis, ___ provides the energy necessary to form a peptide bond between amino acids.
Largest to smalles: codon, gene, chromosome, nucleotide
chromosome -> gene -> codon -> nucleotide
are clusters of ribosomes trailing along the same strand of mRNA, occur in prokaryotes and eukaryotes, increase the efficiency of mRNA translation
In the first steps of protein synthesis the initiation tRNA binds to the P-siet of the large ribosomal subunit. Next, a ___ with proper anticodon comes in to the ___ of the ribosomes and binds with mRNA.
The start codon of ___, AUG, initiates protein synthesis when a complementary tRNA, UAC, binds to it and attaches to the ___ of the ribosome.
A ___ is a portion of a DNA molecule that determines the sequence of amino acids in a polypeptide.
gene; "one gene, only polypeptide"
T/F: All cells have the same genes, but they don't necessarily use the same genes. Most DNA is not being used. EX: skin cells use genes necessary for skin, liver cells use genes necessary for liver
How do eukaryotes control our genes?
Transcription - DNA is packaged and organized into chromatin; Translation - Role of DNA is to make RNA, which is processed and transported out of the nucleus and used to synthesize proteins.
What are the control points of gene expression?
pre-transcriptional, transcriptional, translation, post-translational
The addition of methyl groups (—CH3) to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression (inactive DNA).
the attachment of acetyl groups (-COCH3) to certain amino acids of histones, the chromatin becomes less compact, and the DNA is accessible for transcription
Describe how histone acetylation occurs.
DAn has a negatively charged phosphate backbone. Histones have a high proportion of positively charged amino acids which allow them to bind with DNA. Acetylation changes the histone's shape which loosens its grip on DNA causing the DNA to be transcribed more easily.
proteins that bind the the TATA box and are required for transcription; on transcription factor recognized DNA at the TATA box while the other transcription factors recognize proteins
Transcription factores called ___ bind to the enhancers. The DNA folds over allowing the activators to bind with other transcription factors in the promoter. The transcription initiation complex is formed and transcription takes place.
Enhancers are sequences of DNA that are up to 1000 nucleotides away from the promoter. Transcription factors called activators bind to enhancers and help from the transcription _______.
The attachment of -CH3 to DNA bases to effect longterm DNA activation is called ______.
Transcription factors are regulatory proteins that work with control elements to affect regulation of gene expression. What are the control elements?
The control elements are non-coding regulations of DNA, binding transcription factors, and include enhancers and promoters.
How is translation controlled?
1) in order to initiate translation, a charged RNA and two ribosomal subunits must assemble ton the RNA strand, 2) In addition, initiation forces are required to bring the components together, 3) Translation initiation factors can be inactivated to prevent translation
Beginning -> Middle -> End of Gene Expression
*DNA methylation (-CH3) and histone acetylation (-COCH3) serve as pretranscriptional controls that effect the availability of genes
*Transcription cannot take place without the presence of transcription factors
*The 5' cap and poly A tail function to protect the RNA strand from enzymatic degeneration
*If the 5' cap and poly A tail are worn down, the breakdown of the mRNA will occur and translation will be prevented
After translation, the breakdown of proteins serves as a final control point for gene expression. Ubiquinated proteins are degraded by large enzyme complexes called ___.
What are the steps of protein degradation?
1) cytosolic enzymes attach ubiquitin to protein, 2) a proteasome recognizes protein for degradation, denatures and encapsulates it, 3) enzymatic components of the proteasome chop protein into smaller parts, 4) proteasome and ubiquitin are recycled
T/F: The following plays a role in the regulation of mRNA translation: inactivation of translation factors, global activation of translational factors, binding of regulatory proteins a the 5' end of mRNA.
Normal control mechanisms for the regulations of gene expression in eukaryotes include:
regulation of DNA transcription, regulation of RNA translation, control of protein degradation
Protein making machinery in eukaryotes.
DNA is rod-like, RNA polymerase depends on transcription factors to recognize the promoter, stop sequence of AT rich region and end 10-35 nucleotides later, larger ribosomes, transcription takes place in nucleus and translation takes place in the cytosol, proteins are targeted for the ER by a signal peptide that is recognized b a receptor in the ER membrane
Protein making machinery in prokaryotes.
nucleoid region where single circular DNA is found, RNA polymerase recognizes promoter, transcription stops at the end of the stop sequence, smaller ribosomes, transcription and translation can happen in the same place simultaneously, proteins do not target because there are no membrane bound organelles
Steps of eurkaryotic transcription and translation
DAN transcription -> RNA processing -> transport of RNA fro nucleus to cytoplasm -> formation of ribosomes/RNA complex
What do Mendel's laws of inheritance have to do with gene expression?
the shared genetic information conveyed and expressed by an organism is governed by certain genetic principles; Mendel's three laws
can occur from defects in the chromosomes or changes in the normally occurring DNA sequence (translocation, cross-over mistakes, deletion, aneuploidy, polyploidy, point mutations)
mutation that affects a single nucleotide, usually by substituting one nucleotide for another (sickle cell anemia - caused by a defect in the protein hemoglobin resulting in abnormal blood cells)
Why do most point mutations in humans have no effect on phenotype?
most point mutations occur in portions of the DNA that do not code for proteins
How can some point mutations in coding proteins have no effect on the amino acid sequence that is formed?
several different nucleotide sequences can code for the same amino acid
substitute one base pair for another, result is the same amino acid and has no phenotypic effect
the base pair substitution cause one amino acid to be substituted for another; would cause the synthesis of a full-length protein with a different structure from the normal protein
one or more nucleotide pairs are inserted into the DNA molecule; creates frame shift and no chance of survival
one or more molecule pairs are removed from DNA molecules; creates from shift and no chance of survival
a deletion or insertion of base pairs which alters the reading of the frame (3 at time), producing different amino acids
DNA strands with a chromosome breaking and joining back together is a cause of ______.
___ has rapidly become on of the most widely used techniques in molecular biology because it is rapid, inexpensive, and simple means of reproducing relatively large numbers of copies of DNA molecules from minute quantities of source DNA material, even if it is poor quality.
PCR technology (polymerase chain reaction)
What does the process of PCR involve?
preparation of the samples, the master mix, and the primers, followed by detection and analysis of the reaction products
Describe the PCR method.
It is a cycling reaction in which template DNA is denatured by heating to separate the strands of the molecule. Primer (20 - 30 base fragment of DNA complementary to a region of the template) is annealed to the single-stranded templates. The cycle ends as the primer molecules are elongated by the action of the DNA polymerase to produce molecules that are identical copies of the template.
includes the living community as well as the physical enviroment in which the organisms live
any system with constant change that can adjust to changes without disturbing the entire system
the factor that is the most critical in determining the types of organisms that can exist in an ecosystem
an organism that makes its own food usually using energy from the Sun in a process called photosynthesis
a type of microscopic plankton that can be found in oceans, seas, and freshwater bodies
a consumer that breaks down the complex molecules found in dead organisms and waste matter
the decay process that makes the nutrients contained in waste and dead matter available to producers once again
describes the predator-prey relationship in terms of the effects on the size of both populations
a category of living things that describes the position of an organism in relation to the order of nutrient and energy transfers in an ecosystem
a representation of the pathway taken by nutrients and energy through the trophic levels of an ecosystem
a representation of the nutrient and energy pathways in an ecosystem showing many crosslinked food chains
pyramid of energy
an ecological pyramid that represents the actual number of organisms present in each trophic level
pyramid of numbers
an ecological pyramid that represents the actual number of organisms present in each trophic level
pyramid of biomass
an ecological pyramid that represents a snapshot of the total mass of the living things at each trophic level in a community
huge biome extends in a continuous belt across Canada, Alasks, Asia, and Europe; very little precipitation, permafrost, and small slow-growing plants such as grasses and mosses; the brief summer growing season prevents much tree growth
the biome characterized by acidic soils, dry winters, moderate precipitation, and the growth of conifers: stretchs across the northern parts of North America
the upper layer of vegetation in a forest that can prevent most sunlight from reaching the forest floor if it is think
temperate deciduous forest
the biome characterized by warmer temperatures than the boreal forest and plenty of precipitation thats huge forests of broadleaf trees; covers regions in southeastern Canada, and eastern United States
rare biome characterized by abundant moisture, mild climate, think and rish soil, and the growth of shrubs and small trees; currently found only in British Columbia, Alaska, and Chile
the biome characterized by highest rainfall and high temperatures throughout the year; believed to contain at least half of Earth's biomes
the biome characterized by least precipitation annually and sparse vegetation of small plants specialized to conserve water; occurs in North America
the biome characterized by the presence of permanent ice and no significant vegetation; occurs at the North and South Poles
favours the survival of organisms with traits that make them better adapted to the environment
one species resembles another that is poisonous, dangerous, or distasteful to avoid predation
when a species disappears completely from Earth, or when so few individuals remain that reproduction is not possible
local extinction, which occurs when a species ceases to exist in one area but still exists elsewhere in the world
plays an important ecological role in determining the types and numbers of other species in particular ecosystems
the overall role of an organism in a community, including the range of biotic and abiotic conditions that the organism can tolerate
different species developed adaptations so they dont have to compete for the same resources
when species adapt differently to changes in the environment, and become specialized so they fill different niches and don't compete for the same resources
increase in numbers of individuals with new adaptive traits resulting from natural selection; populations with the new adaptions will proliferate until further slective pressure leads to further adaptions
the first species to arrive and colonize a new environment; over time, the presence of the pioneer species changes the environment, creating acceptable conditons for other species to join it and also thrive
the occupation by plant life in an area where the previous vegetation was destroyed by fire, flooding, landslides, or forest harvesting
Matter that consists of compounds that always contain the elements carbon and hydrogen, although other elements may also be present
The process where plants use the Sun's energy to convert carbon dioxide and water into glucose (carbohydrate) and oxygen
In plant and animal cells, oxygen and carbohydrate (glucose) are combined to make energy, carbon dioxide (waste) and water
Special kind of C reservoir that that stores carbon for long periods or absorbs more CO2 than it releases (forests, oceans)
made of ancient decayed organic remains deep below the surface; high carbon content (oil, natural gas)
allow insolation to reach the Earth, but do not allow all radiation re-emitted by the Earth to escape back to space
the warming effect of GHG's preventing preventing thermal energy from escaping into space
(without oxygen) bacteria in soil or water break down organic matter to release its stored energy
some bacteria in soil or water take nitrogen from the air and turn it into ammonia (NH4)
plants with nodules on their roots where N-fixing bacteria live (peanuts, peas, soybeans, clover, alfalfa)
particles that dissolve in water as rocks weather; are carried into the soil where they become nutrients for plants and organisms
microscopic fungi in soil that help phosphates dissolve in water so plant roots can absorb it
substances added by nature or man to the air, water, soil, or food in high enough concentrations to make organisms unhealthy or kill them; may also destroy habitats and food sources and so endanger populations
when air pollutants (esp. sulfur dioxide) bond with water vapour and fall as rain or snow
measures acidity of a solution; 0 (most acidic) <----> 7 (neutral; pure water)< ----> 14 (most basic or alkaline)
gradual build up of chemicals in the tissues of organisms as they consume pollutants in food, air, or water
organisms higher on the food chain have greater amounts of chemicals building up in their tissues
elements (mid-periodic table; high density) toxic or poisonous to organisms even in very low concentrations
chemicals such as DDT of PBC's that stop the normal functioning of hormones
differences among individuals of a species; results from mutation and sexual reproduction
survival of the fittest
individuals that are better suited to their environment survive and reproduce most successfully; natural selection
individuals that are better suited to their environment survive and reproduce most successfully; survival of the fittest
corresponding structures between two species that reflect common lineage; are equivalent structures between species with common ancestors; may or may not look alike or perform the same function
organ so reduced in size, it does not serve an important function; may be homologous to structures in other organisms; evolutionary leftovers. EX: whale hipbones and human appendix
two organisms that are so similar they can interbreed in nature and produce fertile offspring