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1,013 terms

Ultimate AP Biology Vocabulary Review

A review of all of the Campbell 7th Edition terms for the new 2013 AP Biology Curriculum
Molecule with partial charges. Mixes with water.
No partial charges. Do not mix with water.
Attraction of an atom for electrons in a covalent bond.
Water molecules sticking to each other.
Water molecules sticking to other surfaces.
Something dissolved in a solution.
Dissolving agent of a solution.
Same atoms but different arrangement.
structural isomers
Differ in arrangement of atoms.
geometric isomer
Differ in arrangement around a double bond.
Structures that are like a mirror-image.
alpha glucose
Monomer for starch and glycogen.
beta glucose
Monomer for cellulose and chitin.
Carbohydrate component of plant cell walls.
Storage polysaccharide of plants.
Extremely branched polymer of glucose.
Polysaccharide found in arthropod exoskeletons and fungal cell walls.
Suffix of a sugar.
Glycerol and three fatty acids.
Made of four rings of carbon.
Steroid common in cell membranes, also in many hormones.
peptide bond
Bonds that connect amino acids.
Fredrick Sanger
Determined amino acid sequence of proteins.
disulphide bridges
Reinforce tertiary structure.
primary structure
Chain of amino acids.
secondary structure
Either an alpha helix or beta pleated sheet.
tertiary structure
Results from interactions between side chains.
quaternary structure
Results from two or more polypeptide subunits.
Suffix of a protein.
Bases with a double-ring structure.
Bases with a single-ring structure.
phosphodiester bonds
Bonds between phosphate group and pentose sugar in nucleic acids.
To put together.
To break apart.
dehydration synthesis
Condensation reaction where molecules are connected by loss of a water molecule.
Reaction where water split into two hydrogens and one oxygen; this breaks a polymer.
Metabolic pathways that construct molecules, requiring energy.
Metabolic pathways that break down molecules, releasing energy.
natural selection
A population can change over time if individuals with more fit traits leave more offspring than less fit individuals.
evolutionary adaptation
An accumulation of inherited characteristics that enhance organisms' ability to survive and reproduce in specific environments.
artificial selection
Humans modifying species for desired traits through selective breeding.
decent with modification
Darwin's way of referring to evolution.
Methicillin-resistant Staphylococcus aureus.
Individuals whose inherited traits confer an advantage have a better chance of surviving in a given environment and will leave more offspring.
Similarity resulting from common ancestry.
homologous structures
Same structure, different function. Comes from common ancestor.
comparative embryology
Embryos of vertebrates share many anatomical homologies.
vestigial structures
Are little or no importance to organism, but remain from an ancestor.
Geographic distribution of species.
Change in genetic makeup of a population from generation to generation.
Evolutionary change above the species level.
Group of individuals of the same species living in the same area.
population genetics
Study of allele frequency distribution and change under the influence of evolutionary processes.
gene pool
All the genes in a given population at a given time.
allele frequency
Proportion of an allele in a gene pool.
Hardy-Weinberg Theorem
Helps measure changes in allele frequencies over time . Provides an "ideal" population to use as a basis of comparison.
Changes in the nucleotide sequence in DNA.
sexual recombination
Crossing over and shuffling of genes during meiosis.
genetic drift
Change in allele frequencies due to chance.
bottleneck effect
When a population has been dramatically reduced, and the gene pool is no longer reflective of the original population's.
founder effect
When a small number of individuals colonize a new area; the new gene pool is not reflective of original population.
gene flow
When a population gains or loses alleles., movement of alleles into or out of a population due to the migration of individuals to or from the population.
genetic variation
Heritable variations in a population.
discrete characteristics
Characteristics that are classified on an either-or basis, determined by a single gene locus.
quantitative characteristics
Characteristics that vary along a continuum, usually due to influence of two or more genes.
geographic variation
Difference in variation between population subgroups in different areas.
A graded change in a trait along a geographic axis.
relative fitness
Fitness of a particular genotype.
directional selection
Shift toward a favorable variation.
disruptive selection
Shift toward the extremes.
stabilizing selection
Shift that favors the mean.
heterozygous advantage
Maintains recessive alleles in a population,
sexual selection
Natural selection for mating success.
sexual dimorphism
Differences between the sexes in secondary sexual characteristics.
Origin of new species and the source of biological diversity.
biological species concept
Species is a group of populations whose members have the potential to produce fertile offspring.
reproductive isolation
Barriers that impede members of two different species fro producing fertile offspring.
prezygotic barriers
Barriers that impede mating or hinder fertilization.
habitat isolation
When two species encounter each other only rarely.
temporal isolation
When two species breed at different times of day, season, or years.
behavioral isolation
Incompatible courtship rituals, pheromones, or bird songs.
mechanical isolation
Morphological differences prevent fertilization.
gametic isolation
When sperm can't fertilize the eggs.
postzygotic barriers
Barriers that prevent the hybrid zygote from becoming a fertile adult.
reduced hybrid viability
When the genes of different species interact and impair hybrid development.
reduced hybrid fertility
Sterile hybrids due to uneven chromosome number.
hybrid breakdown
Hybrid is fertile, but when they breed the next generation is sterile.
allopatric speciation
When a population is divided; leads to speciation.
sympatric speciation
Speciation without a divided population.
In plants, the result of an extra set of chromosomes during cell division.
Having more than two sets of chromosomes from a single species.
Sterile hybrid is changed to a fertile polyploid due to mutation ; fertile with each other, but not parent species.
adaptive radiation
Evolution of many new species from a common ancestor as a result of introduction to new environments.
punctuated equilibrium
A model of evolution in which a new species will change the most as it buds from a parent species, and then will change little for the rest of its existence.
A model of evolution in which gradual change over a long period of time leads to biological diversity.
Change in the rate or timing of a developmental event ; an organism's shape depends on relative growth rate of body parts.
allometric growth
Proportioning that gives a body a specific form.
homeotic genes
Genes that determine basic features of where a body part is.
Hox genes
Class of homeotic genes. Changes in these genes can have a profound impact on morphology.
Evolutionary history of a species or group of species.
Analytical approach to understanding the diversity and relationships of present and past organisms.
Anatomical similarity due to convergent evolution.
Analogous structures that have evolved independently.
A classification of organisms into groups based on similarities.
bionomial nomenclature
Scientific name.
First part of scientific name.
specific epithet
Second part of scientific name.
phylogenetic trees
Branching diagrams that depict hypotheses about evolutionary relationships.
Diagram that shows patterns of shared characteristics.
A taxonomic grouping that includes only a single ancestor and all of its descendants.
A phylogenetic classification system that uses shared derived characters and ancestry as the sole criterion for grouping taxa.
monophyletic group
A taxonomic grouping that includes an ancestral species and all of its descendants.
paraphyletic group
A monophyletic group in which some descendants of the common ancestor have been removed.
polyphyletic group
A taxonomic grouping consisting of several species that lack a common ancestor (more work is needed to uncover species that tie them together into a monophyletic clade).
shared primitive character
Trait shared beyond the taxon.
shared derived character
Evolutionary novelty unique to that clade.
Species or group of species closely related to the ingroup.
Diagram in which the length of a branch reflects number of changes in a DNA sequence.
ultrametric trees
Diagram in which length of a branch reflects amounts of actual time.
maximum parsimony
"Occam's Razor." A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts.
maximum likelihood
A principle that states that when considering multiple phylogenetic hypotheses, one should take into account the one that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time.
gene families
Groups of related genes in an organism's genome.
orthologous genes
Homologous genes passed in a straight line from one generation to the next.
paralogous genes
Homologous genes that are found in the same genome as a result of gene duplication.
Miller and Urey Experiment
Experiment that found that organic molecules can form in a strongly reducing atmosphere.
Aggregates of abiotically produced molecules surrounded by a membrane.
Membrane-bound droplets that form when lipids are added to water.
radiometric dating
Dating using decay of radioactive isotopes.
Isotopes that have unstable nuclei and undergo radioactive decay.
Oldest known fossils formed from many layers of bacteria and sediment.
endosymbiotic theory
Ancestors of mitochondria and plastids was prokaryotes that came to live in a host cell.
serial endosymbiosis
Sequence of endosymbiotic events that led to an ancestral eukaryote.
genetic annealing
Horizontal gene transfer between different bacteria and archae.
Collections of autonomously replicating cells.
the three-domain system
Domains Bacteria, Archae, and Eukarya.
Spherical bacteria.
Rod-shaped bacteria.
Spiral bacteria.
When the membrane shrinks away from the cell wall as a result of water loss.
Cell bursting.
Cell wall of prokaryotes, but NOT ARCHAEA. Made of a sugar polymer and polypeptide.
Gram stain
Used to classify prokaryotes based on cell wall composition. Important for antibiotics; some antibiotics work on one but not the other.
Gram-positive bacteria
Bacteria that have simple cell walls with much peptidoglycan.
Gram-negative bacteria
Bacteria that have complex cell walls with less peptidoglycan but with lipopolysaccharides. Very toxic and hard to treat.
Interfere with production of peptidoglycan; harm bacteria but not eukaryotes.
Covers the cell wall in prokaryotes.
Hollow tubes used to move cells or exchange DNA between bacteria by conjunction.
In bacteria, the direct transfer of DNA between two cells that are temporarily joined.
Movement toward or away from a stimulus.
Small rings of DNA found naturally in some bacterial cells in addition to the main bacterial chromosome. Can contain genes for antibiotic resistance, or other "contingency" functions.
A thick-walled protective spore that forms inside a bacterial cell and resists harsh conditions.
Photosynthetic bacteria.
Organisms that use hydrogen sulfide or other chemicals as energy source instead of light.
Domain of unicellular prokaryotes that have cell walls lacking peptidoglycan. Like eukaryotes, DNA contains histone proteins.
Archaea that live in extreme environments.
Archaea that thrive in very hot environments, such as volcanic springs.
Archaea that release methane, a greenhouse gas.
antibiotic resistance
Resistance evolving rapidly in many species of prokaryotes due to overuse of antibiotics, especially in agriculture.
Study of interactions between organisms and the environment.
abiotic factors
Nonliving components of environment.
biotic factors
All the plant and animal life of a particular region.
Biotic factors.
All species that inhabit an area.
The sum of all ecosystems.
biogeographic realms
Broad patterns of distribution due to continental drift and barriers such as deserts and mountain ranges.
Movement of individuals away from centers of high population density or their area of origin.
species transplant
Movement of a species to areas where it was previously absent.
potential range
An area where an organism could potentially survive and reproduce.
actual range
Area an organism actually occupies.
Prevailing weather conditions of an area.
Patterns on the global, regional and local level.
Very fine patterns of climate influenced by features of the environment such as shade ares and wind patterns.
Seasonal changes in warm and cool water layers in lakes.
Major types of ecological association that occupy broad geographic regions.
population density
The size of the population within a particular unit of space.
Pattern of spacing among individuals.
mark-recapture method
A sampling technique used to estimate wildlife populations.
New individuals moving into population. Increases population size.
Movement out of population. Decreases population size.
random dispersion
Random spacing of individuals of the same species within an area.
clumped dispersion
The most common pattern of dispersion; individuals aggregated in patches.
uniform dispersion
The pattern in which individuals are equally spaced throughout a habitat.
Defense of a space against encroachment by other individuals.
Study of vital statistics of a population and how they change over time.
life tables
Age-specific summaries of survival patterns of a population.
A group of individuals of the same age.
survivorship curves
Graph of the proportion of a cohort still alive at each age.
Type I
Curve that shows low death rate at early and mid-life and drops at old age, as seen in humans and large animals.
Type II
Curve that represents constant death rate over lifespan small animals and invertebrates.
Type III
Curve that drops sharply at the start then levels off once individuals reach a critical age, as seen in organisms that produce large numbers of offspring.
reproductive rates
Study of females to determine reproductive output and how it varies with age of female.
reproductive table (fertility schedule)
Age-specific summary of reproductive rates in a population.
life history
Traits that affect an organism's schedule of reproduction and survival.
big-bang reproduction
Species that have only a single reproductive opportunity, such as agave and salmon.
repeated reproduction
Species that reproduce over and over.
Big-bang reproduction.
Repeated reproduction.
per capita offspring
Average number of offspring produced per individual during a specified period of time.
per capita death rate
Expected number of deaths in a population in a specified period of time.
reproductive rate
Difference between per capita birth and per capita death rates.
zero population growth (ZPG)
When per capita birth and death rates are equal. (r = 0)
exponential growth
Population increase under ideal conditions, when r > 0. Forms a J-shaped curve.
logistic growth
When limiting factors restrict size of population to the carrying capacity of the environment. Forms an S-shaped curve.
carrying capacity (K)
Maximum population size that a particular environment can support.
K - selected species
Life history traits sensitive to population density. Small number of large offspring, extensive parental care, repeated reproduction.
r-selected species
Life history traits maximize reproductive success in uncrowded environments. Many small offspring that mature quickly, little if any parental care.
density-independent regulation
When birth or death rates do not change with population density.
density-dependent regulation
When birth or death rates do change with population density.
When many populations are linked.
demographic transition
Movement from a high birth rate, high death rate to a low birth rate, low death rate.
age structure
Relative number of individuals at each age.
infant mortality
Number of infant deaths per thousand live births.
life expectancy at birth
Predicted average length of life at birth.
ecological footprint
Land and water area appropriated by each nation as a resource to consume or to absorb the waste it generates.
interspecific competition
Species compete for a limiting resource. (-/-)
competitive exclusion
Strong competition can lead to local elimination of one of the species.
Competitive Exclusion Principle
Two species competing for same limiting resource cannot coexist in one place; one species will have an advantage that will eventually lead to competitive exclusion
ecological niche
Sum total of a species' use of the biotic and abiotic resources.
Sum total of a species' use of the biotic and abiotic resources; an organism's "role".
fundamental niche
The niche species could potentially occupy.
realized niche
The niche species actually occupies.
resource partitioning
Differentiation of niches that enables similar species to coexist.
character displacement
Tendency of characteristics to be more divergent in sympatric populations than allopatric populations.
cryptic coloration
Camouflage; makes an organism difficult to spot.
aposematic coloration
Bright warning colors in animals with a chemical defense.
Batesian mimicry
Species mimics the appearance of an unpalatable or harmful.
Müllerian mimicry
Two or more unpalatable species resemble each other.
Parasites that live within the body of their host.
Parasites that feed on external surface of host.
Insects that lay eggs on or in living host; larvae feed on body of host, eventually killing it. (+/-)
Interspecific interaction that benefits both species. (+/+)
Interaction between species that benefits one but neither helps or harms the other. (+/0)
Reciprocal evolutionary adaptations of two interacting species.
keystone species
Not necessarily abundant, but exert a strong control on community structure due to a pivotal ecological role.
species diversity
Variety of different kinds of organisms that make up a community.
species richness
Total number of different species.
relative abundance
The proportion of each species.
trophic structure
Feeding relationships between organisms in a community.
primary consumer
secondary consumer
Carnivore that eats herbivores.
tertiary consumer
Carnivore that eats carnivores.
quaternary consumer
Carnivore that eats tertiary consumers.
food web
Linked food chains.
energy hypothesis
Length of a food chain is limited by the inefficiency of energy transfer.
dynamic stability hypothesis
Long food chains are less stable than short chains.
dominant species
Species that are the most abundant or have the most biomass.
Total dry mass of all individuals in a population.
invasive species
Species generally introduced by humans, that take hold outside of their native range.
foundation species
Cause physical changes in environment that affect community structure.
Foundation species have positive effects on other species.
bottom-up model
Unidirectional influence from lower to higher trophic levels. (V --> H)
top-down model
Influence moves from top trophic levels to bottom. (V <-- H)
Technique for restoring eutrophic lakes that reduces populations of algae by manipulating higher-level consumers.
nonequilibrium model
Communities are constantly changing after being buffeted by disturbances.
An event, such as storm, fire, flood, drought, overgrazing or human activity, that changes a community and alters resource availability.
intermediate disturbance
Moderate levels of disturbance can create conditions that foster greater species diversity.
human disturbance
Reduces species diversity in all communities.
ecological succession
Gradual recolonization of a disturbed area; species replaced by other species which are replaced by other species.
primary succession
Succession that begins in a virtually lifeless area.
pioneer species
The first species that colonize new area, such as lichen and mosses.
secondary succession
Succession when an existing community has been cleared, but soil left intact.
equatorial-polar gradients
Species diversity highest at equator, decreases toward poles.
Evaporation of water from soil plus transpiration from plants. Correlates with species richness.
species-area curve
The larger the geographic area, the greater the number of species.
island equilibrium model
Islands great for study due to isolation and limited size; can study species diversity and extinction rates.
Consists of all the organisms living in a community as well as all the abiotic factors with which they interact.
Obtain energy from detritus.
Nonliving organic maters such as remains of dead organisms, feces, fallen leaves, dead wood.
primary production
Amount of light energy converted to chemical energy by autotrophs.
gross primary production (GPP)
Amount of light energy that is converted to chemical energy by photosynthesis.
net primary production (NPP)
Energy used by primary producers for respiration.
light limitation
Depth to which light penetrates limits primary production.
limiting nutrient
Greater limiting factor than light in oceans and lakes.
Sewage and fertilizer runoff adds nutrients to lakes; phytoplankton decreases and cyanobacteria increases.
actual evapotranspiration
Annual amount of water transpired by plants and evaporated from landscape.
secondary production
Amount of chemical energy in consumers' food that is converted to new biomass.
production efficiency
The fraction of energy stored in food that was not used for cell respiration.
trophic efficiency
Percentage of production transferred from one trophic level to the next.
pyramid of energy
90% of all energy is lost between trophic levels.
10% rule
Only 10% of the total energy produced at each trophic level is available to the next level. The amount of energy passed up to the levels of the food pyramid reduces as you go up.
pyramids of biomass
Each on this pyramid tier represents standing crop.
turnover time
Standing crop biomass compared to production.
pyramids of numbers
Number of organisms at each trophic level.
Green World Hypothesis
Terrestrial herbivores consume relatively little plant biomass because they are held in check by predators, parasites and disease.
critical load
The amount of added nutrient that can be absorbed by plants without damaging ecosystem.
biological magnification
Toxins become more concentrated in successive trophic levels.
Greenhouse Effect
Carbon dioxide and water vapor in atmosphere trap infrared radiation, re-reflecting it back toward earth.
ozone layer
Protective layer in atmosphere that shields earth from UV radiation.
conservation biology
Integrates ecology, physiology, molecular biology, genetics and evolutionary biology to conserve biological diversity.
restoration ecology
Applies ecological principles in an effort to return degraded ecosystems to conditions as similar as possible to their natural state.
endangered species
Species that is in danger of extinction throughout all or a significant portion of its range.
threatened species
Species that is likely to become endangered.
Use of living organisms such as prokaryotes, fungi, or plants to detoxify polluted ecosystems.
biological augmentation
Uses organisms to add essential materials to degraded ecosystems.
Structures specialized to perform distinct processes within a cell.
The soluble portion of the cytoplasm, which includes molecules and small particles, such as ribosomes, but not the organelles covered with membranes.
eukaryotic cells
Contain a nucleus and other organelles that are bound by membranes.
The region of the cell between the cell membrane and the nucleus.
plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition.
nuclear envelope
Double membrane perforated with pores that control the flow of materials in and out of the nucleus.
nuclear lamina
A netlike array of protein filaments lining the inner surface of the nuclear envelope; it helps maintain the shape of the nucleus.
A threadlike, gene-carrying structure found in the nucleus. Consists of one very long DNA molecule and associated proteins.
The readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins.
Small, dense region within most nuclei in which the assembly of proteins begins.
endomembrane system
A network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.
Small membrane-bound sac that functions in moving products into, out of, and within a cell.
smooth ER
Synthesis of lipids, phospholipids and steroid sex hormones-help detoxify drugs and poisons (liver cells).
rough ER
A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins.
A protein with one or more carbohydrates covalently attached to it.
transport vesicles
Vesicles in transit from one part of the cell to another.
Golgi apparatus
Stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum.
Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
A cell organelle that contains digestive enzymes.
contractile vacuoles
A membranous sac that helps move excess water out of the cell.
The organelles in which nutrients are converted to energy.
Organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis.
A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide.
Infoldings of the inner membrane of a mitochondrion that houses the electon transport chain and the enzyme catalyzing the synthesis of ATP.
Membranous structures within a chloroplast that serve as the site for light harvesting in photosynthesis.
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.
Network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement.
cytoplasmic streaming
The motion of cytoplasm in a cell that results in a coordinated movement of the cell's contents.
cell wall
Strong layer around the cell membrane in plants, algae, and some bacteria.
When a substance moves from an area of higher concentration to an area of lower concentration. Due to entropy.
The diffusion of water through a selectively permeable membrane.
The diffusion of small solutes through a selectively permeable membrane.
passive transport
Transport of a substance across a cell membrane by diffusion. No cell energy required.
active transport
When a cell gets materials or excretes them by using its own energy, usually through ATP; going against a concentration gradient.
Describes a solution that has a greater concentration of total solute.
Describes a solution that has a lesser concentration of total solute.
Describes solutions that have an equal concentration of total solutes.
turgor pressure
The pressure inside of a cell as a cell pushes itself against the cell wall.
This happens when a cell shrinks inside its cell wall while the cell wall remains intact.
This happens when water moves, but the amount within the cell is constant; no pressure builds.
This happens when a cell swells until pressure bursts it, resulting in cell death.
This happens when a cell shrinks and shrivels; can result in cell death if severe.
water potential
The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure.
solute potential
This measurement has a maximum value of 0; it decreases as the concentration of a solute increases.
pressure potential
This measurement has a minimum value of 0 (when the solution is open to the environment); it increases as pressure increases.
selective permeability
A property of a plasma membrane that allows some substances to cross more easily than others.
Molecules are said to be this when it has regions that are both hydrophilic and hydrophobic.
fluid mosaic model
Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.
integral proteins
Integral proteins that span the membrane.
transmembrane proteins
Integral proteins that span the membrane.
peripheral proteins
The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.
An exchange of molecules (and their kinetic energy and momentum) across the boundary between adjacent layers of a fluid or across cell membranes.
enzymatic activity
A protein built into the membrane with active site exposed.
signal transduction
A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell.
cell-cell recognition
The function of membrane proteins in which some glycoproteins serve as ID tags that are recognized by membrane proteins of other cells.
intercellular joining
The function of membrane proteins in which membrane proteins of adjacent cells hook together, as in gap junctions or tight junctions.
Membrane carbohydrates that are covalently bonded to lipids.
Membrane carbohydrates that are covalently bonded to proteins.
transport protein
A membrane protein, specifically a transport protein, that has a hydrophilic channel that certain molecules or atomic ions use as a tunnel.
channel protein
A membrane protein, specifically a transport protein, that has a hydrophilic channel that certain molecules or atomic ions use as a tunnel.
A membrane protein, specifically a transport protein, that facilitates the passage of water through channel proteins.
carrier protein
A membrane protein, specifically a transport protein, that holds onto molecules and changes their shapes in a way that shuttles them across the membrane.
concentration gradient
A difference in the concentration of a substance across a distance.
The ability of a solution to cause a cell to gain or lose water; depends partly on concentration of nonpenetrating solutes relative to inside of cell.
The control of water balance.
A cell with a cell wall that has a reasonable amount of pressure but is healthy.
facilitated diffusion
Passive diffusion that is aided by transport proteins, but that does not require cellular energy.
membrane potential
The voltage of a plasma membrane.
electrochemical gradient
The combination of forces that acts on membrane potential.
gated channel
A protein channel in a cell membrane that opens or closes in response to a particular stimulus.
electrogenic pump
A transport protein that generates voltage across a membrane, causing a net separation in charge.
proton pump
An electrogenic pump that works largely with H+ ions.
The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient.
Occurs when a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane.
Occurs when a cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane.
Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
A type of endocytosis in which the cell "gulps" droplets of fluid into tiny vesicles.
A type of endocytosis in which the cell acquires bulk quantities of specific substances, even though they may not be very concentrated in the extracellular fluid.
Any molecule that bonds specifically to a receptor site of another molecule.
signal transduction pathway
The process by which a signal on a cell's surface is converted into a specific cellular response.
local regulators
These regulators influence cells in the vicinity of them.
Circulating chemical signals that are formed in specialized cells, travels in body fluids, and act on specific target cells.
Any molecule that bonds specifically to a receptor site of another molecule.
protein kinase
The enzyme that transfers phosphate groups from ATP to protein.
adenylyl cyclase
Converts ATP to cyclic AMP in response to an extracellular signal.
protein phosphatases
Enzymes that can rapidly remove phosphate groups from proteins.
second messengers
Small, non-protein water soluble molecules or ions that send messages throughout the cells by diffusion.
inositol triphosphate
Produced by cleavage of a certain kind of phospholipid in the plasma membrane.
scaffolding proteins
A type of large relay protein to which several other relay proteins are simultaneously attached to increase the efficiency of signal transduction.
Study of the structure of an organism.
Study of the functions an organism performs.
Groups of cells with a common structure and function.
epithelial tissue
Tissue that covers outside of the body and lines organs and cavities.
glandualar epithelia
Tissue that absorbs or secretes chemical solutions.
mucous membrane
Membrane that secretes mucus that lubricates the surface of organs and keeps them moist.
simple epithelium
Single layer of cells.
stratified epithelium
Multiples tiers of cells.
cubiodal epithelium
Dice-shaped cells.
columnar epithelium
Cells shaped like bricks standing on end.
squamous epithelium
Cells that are like floor tiles.
connective tissue
Tissue that functions mainly to bind and support other tissues.
collagenous fibers
Fibers made of collagen.
elastic fibers
Fibers made of elastin.
reticular fibers
Fibers made of collagen fibers that are very thin and branched. Forma tightly woven fabric that joins connective tissue to adjacent tissues.
In connective tissue, cells that secrete the proteins of the fibers.
Amoeboid cells that roam connective tissue and engulf foreign particles and debris of dead cells.
muscle tissue
Tissue made of cells capable of contracting.
nervous tissue
Tissue that senses stimuli and transmits signals.
basement membrane
Cells at the base of an epithelial layer are attached to this.
loose connective tissue
Tissue that binds epithelia to underlying tissues and holds organs in place. Contains collagenous, elastic, and recticular fibers.
fibrous connective tissue
Dense tissue, large number of collagen fibers organized into parallel bundles. Includes ligaments and tendons.
Mineralized connective tissue.
Bone-forming cells.
Connective tissue made of plasma, erythrocytes, leukocytes, and platelets.
adipose tissue
Tissue that stores fat.
Attach muscles to bones.
Join bones to bones at joints.
Made of collagenous fibers in matrix of chondroitin sulfate.
Cells that secrete cartilage.
skeletal muscle
Muscle that is striated, multinucleated.
smooth muscle
Muscle that is not striated, is single nucleated.
cardiac muscle
Muscle that is branched, striated, singe nucleated.
Tissues are organized into:, group of tissues that work together to perform closely related functions.
Sheets of connective tissue in moist or fluid-filled body cavities.
thoracic cavity
cavity housing lungs and heart
abdominal cavity
Cavity housing intestines.
Flow of energy through an animal. Limits its behavior, growth, reproduction.
metabolic rate
Amount of energy an animal uses in a unit of time; the sum of all the energy-requiring biochemical reactions.
Animals that are warmed mostly by heat generated by metabolism.
Animals that gain heat mostly from external sources.
basal metabolic rate (BMR)
The metabolic rate of a nongrowing, resting, fasting, nonstressed endotherm.
standard metabolic rate (SMR)
The metabolic rate of a resting, fasting, nonstressed ectotherm.
interstitial fluid
Watery, internal environment of vertebrates.
"Steady state" or "constant internal milieu".
An animal that uses internal control mechanisms to moderate internal change in the face of external fluctuation.
An animal that allows its internal condition to vary with certain external changes.
negative feedback
A type of regulation that responds to a change in conditions by initiating responses that will counteract the change. Maintains a steady state.
positive feedback
A type of regulation that responds to a change in conditions by initiating responses that will amplify the change. Takes organism away from a steady state.
Process of maintaining an internal temperature within a tolerable range.
Increases in the diameter of superficial blood vessels; cools the body.
Reduces blood flow and heat transfer by decreasing the diameter of superficial blood vessels.
countercurrent heat exchanger
In ectotherms, a circulatory adaptation that is an arrangement of blood vessels that warm or cool the blood.
nonshivering thermogenesis (NST)
When hormones cause mitochondria to produce heat instead of ATP in some mammals.
brown fat
Tissue in neck and between shoulders of some mammals that is specialized for rapid heat production.
Adjusting to a new range of environmental temperatures.
heat-shock proteins
Proteins that help maintain integrity of other proteins that would normally be denatured in extreme heat.
Physiological state in which activity is low and metabolism decreases.
Long-term torpor that is an adaptation to winter cold and food scarcity.
Summer torpor. Enables animals to survive long periods of high temperatures and scarce water supplies.
daily torpor
in small mammals and birds, daily lowering of metabolism that allows them to survive on stored energy
metabolic pathway
Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product.
catabolic pathways
Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.
anabolic pathways
Metabolic pathways that consume energy to build complicated molecules from simpler ones.
The study of how organisms manage their energy resources.
kinetic energy
Energy associated with relative motion of objects.
thermal energy
Kinetic energy associated with the random movement of molecules or atoms.
potential energy
Occurs when an object is not moving, but may still posses energy.
first law of thermodynamics
Energy can be transferred and transformed, but it cannot be created or destroyed.
A measure of disorder or randomness.
second law of thermodynamics
Every energy transfer or transformation increases the entropy of the universe.
free energy
Measures the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell.
endergonic reaction
Reaction that absorbs free energy from its surroundings.
exergonic reaction
Reaction that proceeds with a net release of free energy.
energy coupling
The use of an exergonic process to drive an endergonic one.
ATP (adenosine triphosphate)
Composed of a sugar ribose, nitrogenous base adenine, and a chain of three phosphate groups bonded to it.
The metabolic process of introducing a phosphate group into an organic molecule.
A chemical agent that speeds up a reaction without being consumed by the reaction.
A catalytic protein.
activation energy
The amount of energy needed to push the reactants over an energy barrier.
enzyme-substrate complex
When an enzyme binds to its substrate, it forms:
active site
A pocket or groove on the surface of the enzyme.
induced fit
Brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction.
Non-protein helpers that may be bound tightly to the enzyme as a permanent resident, or may bind loosely and reversibly along with the substrate.
If the cofactor is an organic molecule.
competitive inhibitors
Reduce the productivity of enzymes by blocking substrates from entering active sites.
noncompetitive inhibitors
Impede enzymatic reactions by binding to another part of the enzyme (other than the active site).
allosteric regulation
When a protein's function at one site is affected by the binding of a regulatory molecule to a separate site.
It amplifies the response of enzymes to substrates.
feedback inhibition
A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.
A partial degradation of sugars that occur without the use of oxygen.
cellular respiration
When oxygen is consumed as a reactant along with the organic fuel.
redox reactions
When there is a transfer of one or more electrons from one reactant to another.
Loss of electrons.
Gain of electrons.
reducing agent
A reduces B, which accepts the donated electrons.
oxidizing agent
B oxidizes A by removing A's electrons.
electron transport chain
Breaks the fall of electrons to oxygen in several energy-releasing steps.
Breaking glucose into two molecules of a compound called pyruvate.
citric acid cycle
Completes the breakdown of glucose by oxidizing a derivative of pyruvate to carbon dioxide.
oxidative phosphorylation
When energy is released at each step of the chain is stored in a form the mitochondrion can use to make ATP.
substrate-level phosphorylation
When an enzyme transfers a phosphate group from a substrate molecule.
Is formed when pyruvate first enters into the mitochondria via active transport.
ATP synthase
The enzyme that make ATP from ADPand inorganic phosphate.
When energy is stored in the form of a hydrogen ion gradient across a membrane which is used to drive cellular work.
proton-motive force
Emphasizes the capactiy of the gradient to preform work.
Occurs by fermentation, which generate ATP solely by substrate-level phosphorylation.
alcohol fermentation
When pyruvate is converted to ethanol in 2 steps.
lactic acid fermetation
When pyruvate is reduced directly by NADH to form lactic as am end product, with no release of carbon dioxide.
facultative anaerobes
Can make enough ATP to survive using using fermentation or respiration.
innate immunity
Immunity that is present before exposure and effective from birth. Responds to a broad range of pathogens.
acquired immunity
Immunity that is present only after exposure and is highly specific.
White blood cells.
Protein that is produced by lymphocytes and that attaches to a specific antigen.
Most abundant white blood cell., The most abundant type of white blood cell. Phagocytic and tend to self-destruct as they destroy foreign invaders, limiting their life span to a few days.
complement system
A group of about 30 blood proteins that may amplify the inflammatory response, enhance phagocytosis, or directly lyse extracellular pathogens.
Protein produced by cells in response to being infected by a virus; helps other cells resist the virus.
inflammtory response
Innate response with the purpose of containing a site of damage, localizing the response, eliminating the invader and restore tissue function.
Chemical stored in mast cells that triggers dilation and increased permeability of capillaries.
natural killer (NK) cells
These cells kill cancer cells and cells infected with viruses. They bind to their targets and deliver a lethal burst of chemicals to produce holes in the target cell's membrane leading to its destruction.
Any foreign molecule that is specifically recognized by lymphocytes and elicits an immune response.
Small, accessible portion of an antigen that can be recognized.
B lymphocytes (B cells)
Lymphocyte that matures in the bone marrow and secretes antibodies.
T lymphocytes (T cells)
Lymphocyte that matures in the thymus and acts directly against antigens in cell-mediated immune responses.
Secreted antibodies.
antigen presentation
The process by which an MHC molecule binds to a fragment of an intracellular protein antigen and carries it to the cell surface, where it is displayed and can be recognized by a T cell.
Gland in the thoracic cavity above the heart where T lymphocytes mature.
memory cells
General term for lymphocytes that are responsible for immunological memory and protective immunity.
primary immune response
Immune response the first time the body is exposed to a particular antigen. Does not peak until 10-17 days after exposure.
secondary immune response
Immune response after the body has already been exposed to a specific antigen. Response is faster, of greater magnitude, and more prolonged.
humoral immune response
The branch of acquired immunity that involves the activation of B cells and that leads to the production of antibodies, which defend against bacteria and viruses in body fluids.
cell-mediated immune response
The branch of acquired immunity that involves the activation of cytotoxic T cells, which defend against infected cells.
helper T cells
Activate macrophages, B cells and T cells.
active immunity
A form of acquired immunity in which the body produces its own antibodies against disease-causing antigens.
passive immunity
Immunity conferred by transferring antibodies from an individual who is immune to a pathogen to another individual.
The deliberate exposure of a pathogen to produce memory cells.
Rh factor
Refers to the presence or absence of the Rh antigen on red blood cells.
graft versus host reaction
When lymphocytes in donated bone marrow react against the recipient.
anaphylactic shock
A severe reaction that occurs when an allergen is introduced to the bloodstream of an allergic individual. Characterized by bronchoconstriction, labored breathing, widespread vasodilation, circulatory shock, and sometimes sudden death.
autoimmune diseases
Diseases caused when the immune system loses tolerance for self and turns against certain molecules in the body.
Acquired Immunodeficiency Syndrome (AIDS)
The most advanced, and fatal, stage of an HIV infection.
B cell receptor
The antigen receptor on B cells: a Y-Shaped, membrane-bound molecule consisting of two identical heavy chains and two identical light chains linked by disulfide bridges and containing two antigen-binding sites.
T cell receptor
Antigen receptors on a T cell. Unlike antibodies, T cell receptors are never produced in a secreted form.
major histocompatibility compex (MHC)
Binds to a fragment of an antigen within a cell and presents it on the surface of the membrane.
cytotoxic T cells or "killer T cells"
T cells that directly attack infecting organisms; these cells attack antigen labeled foreign or host tissue.
The secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect.
endocrine system
The system of glands that produce endocrine secretions that help to control bodily metabolic activity.
edocrine glands
Glands that secrete chemicals called hormones directly into the bloodstream.
neurosecretory cells
Neurons that secrete neurohormone rather than neurotransmitter.
paracrine signaling
Signal released from a cell has an effect on neighboring cells.
Chemicals released by the immune system communicate with the brain.
growth factors
Factors that stimulate the cell to divide.
nitric oxide (NO)
Local regulator that regulates blood oxygen levels, A gas produced by many types of cells that functions as a local regulator and as a neurotransmitter.
Modified fatty acids that are produced by a wide range of cells.
endocrine signaling
Specialized cells release hormone molecules into vessels of the circulatory system, by which they travel to target cells in other parts of the body.
Hormone produced by the pancreas that helps to decrease blood sugar.
The antagonist of insulin that helps increase blood sugar. It stimulates the liver to break down glycogen into glucose.
cell differentiation
Cell specialization in structure and function.
The process by which an organism takes shape and the differentiated cells occupy their appropriate locations.
fate maps
A labor-intensive study to produce useful territorial diargams of embryonic development.
pattern formation
The development of a spatial organization of tissues and organs.
positional information
The molecular cues that control pattern formation.
sensory neurons
Neurons that carry incoming information from the sense receptors to the central nervous system.
motor neurons
Neurons that carry outgoing information from the central nervous system to the muscles and glands.
Central Nervous System (CNS)
Includes the brain and spinal cord.
Peripheral Nervous System (PNS)
The sensory and motor neurons that connect the CNS to the rest of the body.
cell body
Contains most of a neuron's organelles and its nucleus.
Highly branched extensions that receive signals from other neurons.
Long nerve fiber that conducts away from the cell body of the neuron.
axon hillock
Cone shaped region of an axon where it joins the cell body.
The junction between two neurons or between a neuron and a muscle.
synaptic terminal
A bulb at the end of an axon in which neurotransmitter molecules are stored and released.
Chemical messengers that cross the synaptic gaps between neurons.
presynaptic cell
The transmitting neuron in a synapse.
postsynaptic cell
The neuron, muscle, or gland cell that receives the signal from a neuron.
membrane potential
The voltage across a cell's plasma membrane.
resting potential
The membrane potential of a neuron that is at rest.
The process during the action potential when sodium is rushing into the cell causing the interior to become more positive.
voltage-gated ion channels
Channels that open or close in response to a change in the membrane potential.
action potential
A neural impulse; a brief electrical charge that travels down an axon.
threshold potential
The minimum membrane potential that must be reached in order for an action potential to be generated.
myelin sheath
A layer of electrical insulation that surrounds the axon.
Type of glial cell in the CNS that wrap axons in a myelin sheath.
Schwann cells
Type of glia in the PNS, Supporting cells of the peripheral nervous system responsible for the formation of myelin.
nodes of Ranvier
Gaps in the myelin sheath to which voltage-gated sodium channels are confined.
synaptic vesicles
Membrane-bounded compartments in which synthesized neurotransmitters are kept.
synaptic cleft
The narrow gap that separates the presynaptic neuron from the postsynaptic cell.
Common vertebrate neurotransmitter, especially in neuromuscular junctions.
A neurotransmitter that affects hunger,sleep, arousal, and mood.
Important neurotransmitter in the CNS that acts on the sympathetic nervous system.
Neurotransmitter secreted by the adrenal medulla in response to stress. Also known as adrenaline.
A precursor of epinephrine that is secreted by the adrenal medulla and also released at synapses.
An inhibitory neurotransmitter in the brain.
The most common neurotransmitter in the brain. Excitatory.
Natural analgesics that decrease pain perception.
Structural and functional unit of nervous system.
effector cells
Muscle cells or gland cells that carry out the body's response to stimuli.
Provide structural and metabolic support for neurons.
glial cells
Cells in the nervous system that support, nourish, and protect neurons.
A cluster of nerve cell bodies, often of similar function, located in the PNS.
white matter
Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.
grey matter
The portions of the central nervous system that are abundant in cell bodies of neurons rather than axons. Unmyelinated.
autonomic nervous system
The part of the nervous system of vertebrates that controls involuntary actions of the smooth muscles and heart and glands.
sympathetic division
The part of the autonomic nervous system that arouses the body to deal with perceived threats.
parasympathetic division
A branch of the autonomic nervous system that maintains normal body functions; it calms the body ever conserves energy.
enteric division
One of three divisions of the autonomic nervous system; consists of networks of neurons in the digestive tract, pancreas, and gallbladder.
Largest part of the brain; responsible for voluntary muscular activity, vision, speech, taste, hearing, thought, and memory.
The largest and most complicated region of the brain, including the thalamus, hypothalamus, limbic system, and cerebrum.
Region between the hindbrain and the forebrain; it is important for hearing and sight.
The posterior portion of the brain including cerebellum and brainstem.
cerebral cortex
Interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center.
The oldest part and central core of the brain, responsible for automatic survival functions.
medulla oblongata
Contains centers that control several visceral functions, including breathing, heart and blood vessel activity, swallowing, vomiting, and digestion.
recticular formation
Registers and controls activity level, increases excitement, and helps generate sleep.
The "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance.
Major input center for sensory information going to the cerebrum and the main output center for motor information leaving the cerebrum.
circadian rhythms
The 24-hour biological cycles found in humans and many other species.
biological clock
An innate mechanism in living organisms that controls the periodicity of many physiological functions.
cerebral hemispheres
The right and left halves of the cerebrum.
corpus callosum
Nerves that enable communication between the right and left cerebral hemispheres.
The way an organism reacts to changes in its internal condition or external environment.
proximate questions
Address environmental stimuli, genetic, physiological, and anatomical causes of a behavior.
ultimate questions
Address evolutionary significance of a behavior.
The scientific study of how animals behave, particularly in natural environments.
fixed action patterns (FAP)
A sequence of unlearned behavioral acts that is unchangeable and usually carried to completion.
sign stimulus
External sensory stimulus that triggers a fixed action pattern.
Includes both learning and innate components, generally irreversible.
sensitive period
A limited phase in an animal's development that is the only time when certain behaviors can be learned.
innate behavior
A behavior that is developmentally fixed.
A simple change in activity or turning rate in response to a stimuli.
Automatic, oriented movement toward or away from some stimuli.
Relatively long-distance movement of individuals, usually on a seasonal basis.
A behavior that causes change in another's behavior.
Signals among animals that include sounds, odors, visual displays, and touches that produce responses.
The modification of behavior based on specific experiences.
A loss of responsiveness to stimuli that convey little or no information.
spatial learning
The modification of behavior based on experience with the spatial structure of the environment.
cognitive maps
An internal representation of the spatial relationships between objects in an animal's surroundings.
associative learning
The ability of animals to associate one feature with another.
classical conditioning
An arbitrary stimulus is associated with an award or punishment.
operant conditioning
Learning based on the consequences of responding.
The ability of an animal's nervous system to perceive, store, process, and use information gathered by sensory receptors.
Behavior associated with recognizing, searching for, capturing, and consuming food.
optimal foraging theory
Views foraging behavior as a compromise between benefits of nutrition and costs of obtaining food.
No strong pair bonds or lasting relationships.
One male mating with one female.
An individual of one sex mating with several of the other.
One male, several females.
One female, several males.
agonistic behavior
Competition that determines who wins a prize, such as food or mates.
game theory
Evaluates alternate strategies when outcome depends not only on each individual's strategy but also that of others.
Behavior that benefits another without benefiting oneself.
inclusive fitness
The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives to increase the production of their offspring.
coefficient of relatedness
Probability that if two individuals share common parent or ancestor, a particular gene present in one will be present in other.
Hamilton's rule
when C < r x B
C = cost to the altruistic party
r = genetic relatedness
B = fitness benefit to recipient of altuism
kin selection
Natural selection that favors altruistic behaviors by enhancing reproductive success of relatives.
social learning
Learning through observing others.
A system of information transfer through influential social learning or teaching.
mate choice copying
Individuals in a population copy mate choice of others.
cell division
The process in reproduction and growth by which a cell divides to form daughter cells.
The ordering of genes in a haploid set of chromosomes of a particular organism.
binary fission
A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size.
somatic cell
Any of the cells of a plant or animal except the reproductive cells.
Threadlike structures made of DNA molecules that contain the genes.
The readily stainable substance of a cell nucleus consisting of DNA and RNA and various proteins.
sister chromatids
Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.
The region of the chromosome that holds the two sister chromatids together during mitosis.
In animal cells, a cytoplasmic organelle that organizes the mitotic spindle fibers during cell reproductions.
cell cycle
Series of events that cells go through as they grow and divide.
Cell division in which the nucleus divides into nuclei containing the same number of chromosomes.
M phase
Mitosis and cytokinesis.
Division of the cytoplasm to form two separate daughter cells.
S phase
The synthesis phase of the cell cycle; the portion of interphase during which DNA is replicated.
G1 phase
The first gap, or growth phase, of the cell cycle, consisting of the portion of interphase before DNA synthesis begins.
G2 phase
The second growth phase of the cell cycle, consisting of the portion of interphase after DNA synthesis occurs.
Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases.
mitotic spindle
An assemblage of microtubules and associated proteins that is involved in the movements of chromosomes during mitosis.
A structure in animal cells containing centrioles from which the spindle fibers develop.
kinetochore microtubules
Connects the centrosome with the kinetochore in the centromere region of the chromosome.
A specialized region on the centromere that links each sister chromatid to the mitotic spindle.
Microtubules and fibers that radiate out from the centrioles.
metaphase plate
Plane midway between the two poles of the cell where chromosomes line up during metaphase.
cleavage furrow
The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate.
cell plate
A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.
density dependent inhibition
The arrest of cell division that occurs when cells grown in a laboratory dish touch one another.
growth factors
Regulatory proteins that ensure that the events of cell division occur in the proper sequence and at the correct rate.
restriction point
A point of no return in the cell cycle; once this point passes, a cell is committed to a full round of the cell cycle.
Complex of cyclin and kinase.
A cyclin-Cdk complex that causes the cell to move from interphase into mitosis.
Any malignant growth or tumor caused by abnormal and uncontrolled cell division.
The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane; specifically.
One of the alternative forms of a gene that governs a characteristic, such as hair color.
alteration of generations
The alteration of two or more different forms in the life cycle of a plant or animal.
asexual reproduction
One parent produces a genetically identical offspring by mitosis.
Chromosomes that are not directly involved in determining the sex of an individual.
X-shaped regions where crossing over occurred.
An identical genetically individual of the parent
crossing over
Nonsister chromatids exchanging DNA segments.
diploid cell
Has two sets of chromosomes.
Union of gametes.
A haploid cell such as an egg or sperm that unite during sexual reproduction to produce a diploid zygote.
The stage in the life cycle of a plant in which the plant produces gametes, or sex cells.
Units of heredity made up of DNA.
Scientific study of heredity and variation.
One set of chromosomes.
Transmission of traits from one generation to the next.
homologous chromosomes
Pair of chromosomes that are the same size, same appearance and same genes.
independent assortment
The random distribution of the pairs of genes on different chromosomes to the gametes.
Photograph of chromosomes grouped in order and in pairs.
life cycle
All of the events in the growth and development of an organism until the organism reaches sexual maturity.
The specific site of a particular gene on its chromosome.
nonsister chromatids
Different chromatids (maternal and paternal) of the same chromosome.
recombinant chromosomes
Chromosomes that carry genes from each parent.
sex chromosomes
X and Y chromosomes.
sexual reproduction
When two parents give unique combination of genes to offspring.
Produced by meiosis. Grow into haploid organisms by mitosis.
Diploid, or spore-producing, phase of an organism. Makes haploid spores by meiosis.
Homologous chromosomes pair up, aligned gene by gene.
A pair of chromosomes form tetrads made up of four chromatids.
Fertilized egg. Carries one set of chromosomes from each parent.
Is demonstrated by the differences in appearance that offspring show from parents and siblings.
A heritable feature that varies among individuals.
Each variant of a character.
Organisms that, when reproducing, create offspring of all the same variety.
The crossing of two true-breeding parents.
P generation
The name for the true-breeding parents.
F1 Generation
The hybrid offspring of true-breeding parents.
F2 Generation
After the self-pollenization of the F1 generation, this is produced.
The Law of Segregation
Two alleles separate during gamete formation and end up in different gametes because they are on on homologous chromosomes.
dominant allele
An allele whose trait always shows up in the organism when the allele is present.
recessive allele
An allele that is masked when a dominant allele is present
Punnett square
A diagram for predicting the allele composition of offspring from a cross between individuals of known genetic makeup.
An organism having a pair of identical alleles for a character, either dominant or recessive.
An organism's traits.
An organism's genetic makeup.
The result of breeding a recessive homozygote with an organism of dominant phenotype but unknown genotype.
Parents that are heterozygous for one character.
Parents that are heterozygous for two characters.
multiplication rule
To determine the probability, we multiply the probability of one event by the probability of another.
addition rule
Considering mutually exclusive events, the probability of both occurring is the sum of the probabilities of each event.
complete dominance
When the phenotypes of the heterozygote and dominant homozygote are indistinguishable.
When which the phenotypes of both alleles are exhibited in the heterozygote.
incomplete dominance
Creates a blended phenotype; one allele is not completely dominant over the other.
Tay-Sachs disease
A human genetic disease caused by a recessive allele that leads to the accumulation of certain lipids in the brain. Seizures, blindness, and degeneration of motor and mental performance usually become manifest a few months after birth.
quantitative characters
Characters that vary in the population along a continuum (in gradations).
polygenic inheritance
An additive effect of two or more genes on a single phenotypic character.
A diagram that shows the occurrence of a genetic trait in several generations of a family.
cystic fibrosis
A genetic disorder that is present at birth and affects both the respiratory and digestive systems.
sickle-cell disease
Genetic disorder in which red blood cells have abnormal hemoglobin molecules and take on an abnormal shape.
Huntington's disease
Genetic disorder that causes progressive deterioration of brain cells. caused by a dominant allele. symptoms do not appear until about the age of 30.
Prenatal diagnostic technique that involves inserting a needle to obtain a sample of amniotic fluid that surrounds the fetus.
chorionic villus sampling (CVS)
Prenatal diagnostic technique that involves taking a sample of tissue from the chorion.
chromosome theory of inheritance
According to this theory, genes are carried from parents to their offspring on chromosomes.
XY system
A sex determination system in which females have two of the same kind of sex chromosome and males have two different ones.
XO system
A sex determination system in some insects in which O stands for the absence of a sex chromosome. Females are XX, Males are XO. Males produce two classes of sperm: X sperm and sperm with no chromosome. The sperm determines the sex of the offspring.
ZW system
A sex determination system in fish, butterflies, birds where males are ZZ and Females are ZW. The egg determines the sex of the offspring.
haplo diploid system
A sex determination system in most species of bees and ants in which there are no sex chromosomes. Females develop from fertilized eggs (diploid) and males develop from unfertilized eggs (haploid).
sex linked genes
Genes located on the sex chromosomes.
X linked genes
Genes found on the X chromosome.
Duchenne muscular dystrophy
A human genetic disease caused by a sex-linked recessive allele; characterized by progressive weakening and a loss of muscle tissue.
barr body
A dense body formed from a deactivated X chromosome.
An X-linked recessive disorder in which blood fails to clot properly, leading to excessive bleeding if injured.
linked genes
Genes located on the same chromosome that tend to be inherited together in genetic crosses.
genetic recombination
The regrouping of genes in an offspring that results in a genetic makeup that is different from that of the parents.
parental types
Offspring with a phenotype that matches one of the parental phenotypes.
recombinant types
Offspring who have inherited new combinations of genes and have phenotypes that don't match either parental phenotypes.
crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
genetic map
An ordered list of the genetic loci along a particular chromosome.
linkage map
A genetic map based on recombination frequencies.
map units
A measurement of the distance between genes; one map unit is equivalent to a 1 percent recombination frequency.
Error in meiosis in which homologous chromosomes fail to separate.
Abnormal number of chromosomes.
A chromosomal condition in which a particular cell has only one copy of a chromosome, instead of the normal two.
A chromosomal condition in which a particular cell has an extra copy of one chromosome, instead of the normal two.
A type of mutation in which the order of the genes in a section of a chromosome is reversed.
A change to a chromosome in which a fragment of the chromosome is removed.
Change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome.
Downs Syndrome
A congenital disorder caused by having an extra Chromosome 21.
genomic imprinting
Variation in phenotype depending on whether an allele is inherited from the male or female parent.
cytogenetic maps
A chart of a chromosome that locates genes with respect to chromosomal features distinguishable in a microscope.
A change in genotype and phenotype due to the assimilation of external DNA by a cell.
A virus that infects bacteria; also called a phage.
semiconservative model
Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand.
origins of replication
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.
replication fork
A Y-shaped region on a replicating DNA molecule where new strands are growing.
DNA polymerase
An enzyme that catalyzes the formation of the DNA molecule.
lagging strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5' to 3' direction away from the replication fork.
leading strand
The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.
Okazaki fragments
Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.
An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
An enzyme that untwists the double helix at the replication forks, separating the two parental strands and making them available as template strands.
single-strand binding protein (SSB)
Binds to and stabilizes single-stranded DNA until it can be used as a template.
A DNA cutting enzyme that excises damaged DNA.
Repeated DNA sequences at the ends of eukaryotic chromosomes.
An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.
Watson and Crick
Developed the double helix model of DNA.
Hersey-Chase Experiment
Devised an experiment that showed that only the DNA of T2 phages enters a bacterial cell during infection.
Frederick Griffith
Discovered transformation during an experiment that involved injecting mice with smooth S cells, rough R cells, heat-killed S cells, and heat-killed S cells with living R cells.
McCarty, Avery, & MacLeod
Confirmed that the transforming agent in Griffith's experiment was DNA.
one gene-one polypeptide hypothesis
The premise that a gene is a segment of DNA that codes for one polypeptide.
Synthesis of an RNA molecule from a DNA template.
messenger RNA (mRNA)
Carries genetic message from the DNA to he protein-synthesizing machinery of the cell.
Erwin Chargaff
Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine.
Meselson & Stahl
Determined that DNA replication is semiconservative.
The synthesis of a polypeptide, which occurs under the direction of mRNA.
Complex particles that facilitate the orderly linking of amino acids into polypeptide chains.
RNA processing
The modification of mRNA before it leaves the nucleus that is unique to eukaryotes.
primary transcript
The initial mRNA transcript that is transcribed from a protein coding gene. Also called pre-mRNA.
triplet code
Three-nucleotide long set that specifies a specific amino acid for a polypeptide chain.
template strand
The DNA strand that provides the template for ordering the sequence of nucleotides in an mRNA transcript.
TATA box
A promoter DNA sequence crucial in forming the transcription initiation complex.
A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing mRNA.
RNA polymerase
Enzyme that links together the growing chain of ribonucleotides during transcription.
poly-A tail
Modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides.
In prokaryotes, a special sequence of nucleotides in DNA that marks the end of a gene.
5' cap
The 5' end of a pre-mRNA molecule modified by the addition of a cap of guanine nucleotide.
Coding segments of eukaryotic DNA.
Specialized base triplet at one end of a tRNA molecule that recognizes a particular complementary codon on an mRNA molecule.
one gene-one polypeptide hypothesis
there is one gene that codes for one polypeptide
mRNA base triplets.
reading frame
Reading mRNA nucleotides in the correct groupings.
transcription factors
Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription.
transcription initiation complex
The assembly of transcription factors and RNA polymerase.
RNA splicing
Process by which the introns are removed from RNA transcripts and the remaining exons are joined together.
Noncoding segments of nucleic acid that lie between coding sequences.
Different particles that recognize splice sites are compiled in a large assembly. A complex of RNA and protein subunits. Removes introns from a transcribed pre-RNA segments.
RNA molecules that function as enzymes.
alternative RNA splicing
Genes giving rise to two or more different polypeptides depending upon which segments are treated as exons.
Discrete structural and functional regions of proteins.
transfer RNA (tRNA)
Interpreter of a series of codons along a mRNA molecule.
Flexibility in the base-pairing rules in which the nucleotide at the 5' end of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position of a codon.
ribosomal RNA (rRNA)
RNA molecules that construct ribosomal subunits.
ribosomal P site
Site that holds tRNA carrying the growing polypeptide chain.
ribosomal A site
Site that holds the tRNA carrying the next amino acid to be added to the chain.
Ribosomal E site
Site where discharged tRNAs leave the ribosome.
Strings of ribosomes that work together to translate a RNA message.
signal peptide
A stretch of amino acids on a polypeptide that targets the protein to a specific destination in a eukaryotic cell.
signal-recognition particle
A protein-RNA complex that recognizes a signal peptide as it emerges from the ribosome.
Random errors in gene replication that lead to a change in the sequence of nucleotides. The source of all genetic diversity.
point mutations
chemical changes in just one base pair of a gene
missense mutations
Most common type of mutation, a base pair mutation in which the new codon makes sense in that it still codes for an amino acid.
nonsense mutations
A mutation that changes an amino acid codon to one of three stop codons, resulting in a shorter and usually nonfunctional protein.
frameshift mutation
Mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in improper grouping of nucleotides into codons.
physical and chemical agents that interact with DNA to cause mutations
A protein that binds to DNA and stimulates transcription of a specific gene.
A virus that infects bacteria; also called a phage.
The protein shell that encloses a viral genome. It may be rod-shaped, polyhedral, or more complex in shape.
cyclic AMP (cAMP)
A compound formed from ATP that acts as a second messenger.
A genetic element that can exist either as a plasmid or as part of the bacterial chromosome.
F factor
A piece of DNA that confers the ability form a sex pili.
F plasmid
The plasmid form of the F factor.
HIV (human immunodeficiency virus)
The infectious agent that causes AIDS. HIV is a retrovirus.
host range
The limited range of host cells that each type of virus can infect and parasitize.
A specific small molecule that inactivates the repressor in an operon.
insertion sequence
The simplest kind of transposable element, consisting of inverted repeats of DNA flanking a gene for transposase, the enzyme that catalyzes transposition.
lysogenic cycle
A phage replication cycle in which the viral genome becomes incorporated into the bacterial host chromosome as a prophage and does not kill the host.
lytic cycle
A type of viral (phage) replication cycle resulting in the release of new phages by lysis (and death) of the host cell.
A dense region of DNA in a prokaryotic cell.
Region of DNA that controls RNA polymerase's access to a set of genes with related functions.
A unit of genetic function common in bacteria and phages, consisting of coordinately regulated clusters of genes with related functions.
A small ring of DNA that carries accessory genes separate from those of a bacterial chromosome; also found in some eukaryotes, such as yeast.
A phage genome that has been inserted into a specific site on the bacterial chromosome.
Viral DNA that inserts into a host genome.
R plasmid
A bacterial plasmid carrying genes that confer resistance to certain antibiotics.
regulatory gene
A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
A protein that suppresses the transcription of a gene.
An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses.
reverse transcriptase
An enzyme encoded by some certain viruses (retroviruses) that uses RNA as a template for DNA synthesis.
temperate phage
A phage that is capable of reproducing by either the lytic or lysogenic cycle.
transposable genetic element
A segment of DNA that can move within the genome of a cell by means of a DNA or RNA intermediate; also called a transposable element.
A transposable genetic element that moves within a genome by means of a DNA intermediate.
A harmless variant or derivative of a pathogen that stimulates a host's immune system to mount defenses against the pathogen.
viral envelope
A membrane that cloaks the capsid that in turn encloses a viral genome.
cell differentiation
the process by which a cell becomes specialized for a specific structure or function.
gene expression
Conversion of the information encoded in a gene first into messenger RNA and then to a protein.
differential gene expression
The expression of different sets of genes by cells with the same genome.
histone acetylation
The attachment of acetyl groups to certain amino acids of histone proteins.
DNA methylation
The addition of methyl groups to bases of DNA after DNA synthesis; may serve as a long-term control of gene expression.
epigenetic inheritance
Inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.
control elements
segments of noncoding DNA in eukaryotic genes that help regulate transcription by binding to certain proteins.
A DNA segment containing multiple control elements that can recognize certain transcription factors that stimulate the transcription of nearby genes.
micro-RNA (miRNA)
small single stranded RNA molecules that bind to mRNA and can degrade mRNA or block its translation.
siRNAs (small interfering RNAs)
RNAs of similar size and functions as miRNAs that inhibit gene expression.
A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin.
RNA interference
Blocking gene expression by means of an miRNA silencing complex.
recombinant DNA
A DNA molecule made in vitro with segments from different sources.
The manipulation of living organisms or their components to produce useful products.
gene cloning
The production of multiple copies of a gene.
restriction enzyme
A degradative enzyme that recognizes and cuts up DNA (including that of certain phages) that is foreign to a bacterium.
restriction site
A specific sequence on a DNA strand that is recognized as a cut siteby a restriction enzyme.
restriction fragment
The fragment of DNA that is produced by cleaving DNA with a restriction enzyme.
sticky end
A single-stranded end of a double-stranded DNA restriction fragment.
DNA ligase
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain.
cloning vector
DNA molecules that can carry foreign DNA into a host cell and replicate there.
nucleic acid hybridization
Base pairing between a gene and a complementary sequence on another nucleic acid molecule.
nucleic acid probe
Radioactively labeled nucleic acid molecule used to tag a particular DNA sequence.
In proteins, a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix.
genomic library
A set of thousands of DNA segments from a genome, each carried by a plasmid, phage, or other cloning vector.
complementary DNA (cDNA)
DNA molecule made in vitro using mRNA as a template and the enzyme reverse transcriptase.
cDNA library
A limited gene library using complementary DNA. The library includes only the genes that were transcribed in the cells examined.
expression vector
A cloning vector that contains the requisite prokaryotic promoter just upstream of a restriction site where a eukaryotic gene can be inserted.
yeast artificial chromosome (YAC)
A cloning vector that has telomeres and a centromere that can accommodate large DNA inserts and uses the eukaryote yeast as a host cell.
A technique to introduce recombinant DNA into cells by applying a brief electrical pulse to a solution containing the cells. The pulse creates temporary holes in the cells' plasma membrane, through which DNA can enter.
polymerase chain reaction (PCR)
A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides.
gel electrophoresis
The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.
Southern blotting
A hybridization technique that enables researchers to determine the presence of certain nucleotide sequences in a sample of DNA.
restriction fragment length polymorphisms (RFLPs)
differences in the restriction sites on homologous chromosomes that result in different restriction fragment patterns.
Human Genome Project
An international collaborative effort to map and sequence the DNA of the entire human genome.
linkage map
A genetic map based on the frequencies of recombination between markers during crossing over of homologous chromosomes.
physical map
A genetic map in which the actual physical distances between genes or other genetic markers are expressed, usually as the number of base pairs along the DNA.
bacterial artificial chromosome (BAC)
An artificial version of a bacterial chromosome that can carry inserts of 100, 000 to 500, 000 base pairs.
DNA sequencing
Determining the exact order of the base pairs in a segment of DNA.
genetic engineering
The direct manipulation of genes for practical purposes.
genomic equivalence
All cells in an organism contain the same complement of genes. These are the same set of genes that are established in the fertilized egg.
Cells that are able to develop into any type of cell found in the body.
Making a genetically identical copy of DNA or of an organism.
nuclear transplantation
A technique in which the nucleus of one cell is placed into another cell that already has a nucleus or in which the nucleus has been previously destroyed.
reproductive cloning
Using a somatic cell from a multicellular organism to make one or more genetically identical individuals.
stem cell
Unspecialized cell that can both reproduce itself indefinitely and differentiate into specialized cells of one or more types.
Able to give rise to multiple, but not all, cell types.
therapeutic cloning
The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the generation of embryonic stem cells to treat disease.
The point during development at which a cell becomes committed to a particular fate due to cytoplasmic effects or to induction by neighboring cells.
cytoplasmic determinants
Maternal substances in egg that influence the course of early development.
The process by which neighboring cells can influence the determination of a cell.
Organisms that use light as a source of energy to synthesize organic substances.
The major sites of photosynthesis in most plants.
Green pigment located within the chloroplasts.
Spongy tissue in the interior of the leaf where most chloroplasts are found.
Microscopic pores in the leaf which lets CO2 in and O2 out. Also where water is lost.
Bundles of xylem and phloem.
Stack of thylakoids.
Fluid inside the chloroplast where the Calvin Cycle happens.
Flattened membranes in the chloroplast where the light reactions take place.
Equation of photosynthesis.
light reaction
Part of photosynthesis that involves light. ATP and NADPH are produced. Takes place on the thylakoid membrane.
Molecules that absorb, reflect, or transmit light.
A cluster of pigments embedded into a thylakoid membrane.
oxidizing agent
Accepts electrons and becomes reduced.
reducing agent
Donates electrons and becomes oxidized.
noncyclic photophosphorolation
Photosystem II performs photolysis to provide electrons for the electron transport chain that drives a chemiosmotic gradient that produces ATP.
cyclic photophosphorolation
Only Photosystem I works. ATP is made, no oxygen is produced, no water is split, no NADPH is made.
In the thylakoid membranes of a chloroplast during light-dependant reactions, two molecules of water are split to form oxygen, hydrogen ions, and electrons.
Process of adding a phosphate group.
carbon fixation
The initial incorporation of carbon into organic compounds.
calvin cycle
Carbon fixation process in photosynthesis. Forms sugar and other organic compounds.
absorption spectrum
A graph plotting a pigment light light absorption.
action spectrum
A profile of the relative performance of the different wavelengths in photosynthesis.
chlorophyll a
Only pigment that can participate directly in the light reactions.
Accessory pigments that broaden the spectrum of colors that can drive photosynthesis.
Reaction center chlorophyll in the photosystem II.
Reaction center cholophyll in the photosystem I.
reaction center
The location of the first light driven chemical reaction of photosynthesis.
primary electron acceptor
Specialized molecule that shares a reaction center with the chlorophyll a molecule in the light reaction. traps high energy electron before it can return to ground state in the chlorophyll.
Process by which a Hydrogen pump pumps protons into the thylakoid membrane. H+ passively flows through the ATP synthase which leads to the creation of ATP.
The most abundant protein on earth. Performs Carbon Fixation in the Calvin Cycle.
A modified leaf in angiosperms that helps enclose and protect a flower bud before it opens.
A modified leaf of a flowering plant; petals are the often colorful parts of a flower that advertise it to insects and other pollinators.
The pollen-producing reproductive organ of a flower, consisting of an anther and a filament.
The ovule-producing reproductive organ of a flower, consisting of the stigma, style, and ovary.
The base of a flower; the part of the stem that is the site of attachment of the floral organs.
In an angiosperm, the terminal pollen sac of a stamen, where pollen grains containing sperm-producing male gametophytes form.
In flowers, the portion of a carpel in which the egg-containing ovules develop.
The stalk of a flower's carpel, with the ovary at the base and the stigma at the top.
The sticky part of a flower's carpel, which receives pollen grain.
A structure that develops within the ovary of a seed plant and contains the female gametophyte.
A single carpel or a group of fused carpels in a flower.
complete flower
A flower that has all four basic floral organs: sepals, petals, stamens, and carpels.
incomplete flower
A flower in which one or more of the four basic floral organs such as sepals, petals, stamens, or carpels are either absent or nonfunctional.
A group of flowers tightly clustered together.
If staminate and carpellate flowers are on the same plant.
If staminate and carpellate flowers are on different plants.
The ability of a seed plant to reject its own pollen and sometimes the pollen of closely related individuals.
In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. Provides nourishment to the developing embryo in angiosperm seeds.
double fertilization
A mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the embryo sac to form the zygote and endosperm.
pollen tube
A tube that forms after germination of the pollen grain and that functions in the delivery of sperm to the ovule.
seed coat
A tough outer covering of a seed, formed from the outer coat of an ovule.
The part of a plant embryo directly below the cotyledons, forming a connection with the radicle.
An embryonic root of a plant.
Covers and protects the shoot as it grows upward.
A mature ovary of a flower that protects dormant seeds and often aids in their dispersal.
simple fruit
A fruit derived from a single carpel or several fused carpels.
aggregate fruit
A fruit derived from a single flower that has more than one carpel.
multiple fruit
A fruit derived from an entire inflorescence.
A condition typified by extremely low metabolic rate and a suspension of growth and development.
Plant morphological adaptations for growing in darkness.
The changes a plant shoot undergoes in response to sunlight; also known informally as greening.
A growth response that results in the curvature of whole plant organs toward or away from stimuli owing to differential rates of cell elongation.
Growth of a plant shoot toward or away from light.
Indoleacetic acid (IAA), a natural plant hormone that has a variety of effects, including cell elongation, root formation, secondary growth, and fruit growth.
A class of plant hormones that retard aging and act in concert with auxin to stimulate cell division, influence the pathway of differentiation, and control apical dominance.
A class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development.
abscisic acid (ABA)
A plant hormone that slows down growth, promotes seed dormancy and facilitates drought tolerance.
The only gaseous plant hormone. Among its many effects are response to mechanical stress, programmed cell death, leaf abscission, and fruit ripening.
triple response
A plant growth maneuver in response to mechanical stress, involving slowing of stem elongation, a thickening of the stem, and a curvature that causes the stem to start growing horizontally.
Programmed cell death.
leaf abscission
Aging and dropping of leaves controlled by auxin and ethylene.
fruit ripening
A burst of ethylene production in a fruit triggers the ripening process.
Effects of light on plant morphology.
blue-light photoreceptors
A class of light receptors in plants. Blue light initiates a variety of responses, such as phototropism and slowing of hypocotyl elongation.
A class of light receptors in plants. Mostly absorbing red light, these photoreceptors regulate many plant responses, including seed germination and shade avoidance.
circadian rhythm
A physiological cycle of about 24 hours that is present in all eukaryotic organisms and that persists even in the absence of external cues.
A physiological response to photoperiod, the relative lengths of night and day. An example of photoperiodism is flowering.
short-day plant
A plant that flowers only when the light period is shorter than a critical length. Usually fall or winter.
long-day plant
A plant that flowers only when the light period is longer than a critical length. Usually spring or early summer.
day-neutral plant
A plant whose flowering is not affected by photoperiod.
The use of cold treatment to induce a plant to flower.
A flowering signal, not yet chemically identified, that may be a hormone or may be a change in relative concentrations of multiple hormones.
jasmonic acid
An important molecule in plant defense against herbivores.
A term describing a pathogen against which a plant has little specific defense.
A term describing a pathogen that can only mildly harm, but not kill, the host plant.
gene-for-gene recognition
A widespread form of plant disease resistance involving recognition of pathogen-derived molecules by the protein products of specific plant disease resistance genes.
A molecule that induces a broad type of host defense response
A type of elicitor that is derived from cellulose fragments released by cell wall damage
PR protein
A protein involved in plant responses to pathogens (PR = pathogenesis-related).
hypersensitive response (HR)
A plant's localized defense response to a pathogen
systemic acquired resistance (SAR)
A defensive response in infected plants that helps protect healthy tissue from pathogenic invasion.
salicylic acid
A plant hormone that may be partially responsible for activating systemic acquired resistance to pathogens.
The target cell's detection of a signal molecule coming from outside the cell.
The binding of the signal molecule changes the receptor protein in some way.
The transduced signal finally triggers a specific cellular response.
G-protein-linked receptor
A plasma membrane receptor that works with the help of a G-protein.
receptor tyrosine kinase
A receptor with enzymatic activity that can trigger more than one signal transduction pathway at once, helping the cell regulate and coordinate many aspects of cell growth and reproduction.
ligand-gated ion channel
Type of membrane receptor that has a region that can act as a "gate" when the receptor changes shape.
diacylglycerol (DAG)
A second messenger produced by the cleavage of a certain kind of phospholipid in the plasma membrane.
Enzyme that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.
The complex of DNA and proteins that makes up a eukaryotic chromosome.
Stem cells with the potential to differentiate into any type of cell.
Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.
Viruses that reproduce only by the lytic cycle.