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P generation The name for the true-breeding parents.
p680 Reaction center chlorophyll in the photosystem II.
p700 . Reaction center cholophyll in the photosystem I
paracrine signaling Signal released from a cell has an effect on neighboring cells.
paralogous genes Homologous genes that are found in the same genome as a result of gene duplication.
paraphyletic group A monophyletic group in which some descendants of the common ancestor have been removed.
parasitoidism Insects that lay eggs on or in living host; larvae feed on body of host, eventually killing it. (+/-)
parasympathetic division A branch of the autonomic nervous system that maintains normal body functions; it calms the body ever conserves energy.
parental types Offspring with a phenotype that matches one of the parental phenotypes.
passive immunity Immunity conferred by transferring antibodies from an individual who is immune to a pathogen to another individual.
passive transport Transport of a substance across a cell membrane by diffusion. No cell energy required.
pattern formation The development of a spatial organization of tissues and organs.
pedigree A diagram that shows the occurrence of a genetic trait in several generations of a family.
peptide bond Bonds that connect amino acids.
peptidoglycan Cell wall of prokaryotes, but NOT ARCHAEA. Made of a sugar polymer and polypeptide.
per capita death rate Expected number of deaths in a population in a specified period of time.
per capita offspring Average number of offspring produced per individual during a specified period of time.
Peripheral Nervous System (PNS) The sensory and motor neurons that connect the CNS to the rest of the body.
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.
peroxisome A microbody containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide.
petal A modified leaf of a flowering plant; petals are the often colorful parts of a flower that advertise it to insects and other pollinators.
phagocytosis Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
phagocytosis Process in which extensions of cytoplasm surround and engulf large particles and take them into the cell.
phenotype An organism's traits.
phosphodiester bonds Bonds between phosphate group and pentose sugar in nucleic acids.
phosphoralation Process of adding a phosphate group.
phosphorylation The metabolic process of introducing a phosphate group into an organic molecule.
photoautotrophs Organisms that use light as a source of energy to synthesize organic substances.
photoautotrophs Photosynthetic bacteria.
photolysis In the thylakoid membranes of a chloroplast during light-dependant reactions, two molecules of water are split to form oxygen, hydrogen ions, and electrons.
photomorphogenesis Effects of light on plant morphology.
photoperiodism A physiological response to photoperiod, the relative lengths of night and day. An example of photoperiodism is flowering.
photosystem A cluster of pigments embedded into a thylakoid membrane.
phototropism Growth of a plant shoot toward or away from light.
phylogenetic trees Branching diagrams that depict hypotheses about evolutionary relationships.
phylogeny Evolutionary history of a species or group of species.
phylograms Diagram in which the length of a branch reflects number of changes in a DNA sequence.
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.
physiology Study of the functions an organism performs.
phytochromes . A class of light receptors in plants. Mostly absorbing red light, these photoreceptors regulate many plant responses, including seed germination and shade avoidance
pigments Molecules that absorb, reflect, or transmit light.
pilli Hollow tubes used to move cells or exchange DNA between bacteria by conjunction.
pinocytosis A type of endocytosis in which the cell "gulps" droplets of fluid into tiny vesicles.
pioneer species The first species that colonize new area, such as lichen and mosses.
pistil A single carpel or a group of fused carpels in a flower.
plasma membrane The membrane at the boundary of every cell that acts as a selective barrier, thereby regulating the cell's chemical composition.
plasmid A small ring of DNA that carries accessory genes separate from those of a bacterial chromosome; also found in some eukaryotes, such as yeast.
plasmids 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.
plasmolysis This happens when a cell shrinks inside its cell wall while the cell wall remains intact.
plasmolyze When the membrane shrinks away from the cell wall as a result of water loss.
pluripotent Able to give rise to multiple, but not all, cell types.
point mutations chemical changes in just one base pair of a gene
polar Molecule with partial charges. Mixes with water.
pollen tube A tube that forms after germination of the pollen grain and that functions in the delivery of sperm to the ovule.
poly-A tail Modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides.
polyandry One female, several males.
polygamous An individual of one sex mating with several of the other.
polygenic inheritance An additive effect of two or more genes on a single phenotypic character.
polygyny One male, several females.
polymerase chain reaction (PCR) A technique for amplifying DNA in vitro by incubating with special primers, DNA polymerase molecules, and nucleotides.
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).
polyploidy In plants, the result of an extra set of chromosomes during cell division.
polyribosomes Strings of ribosomes that work together to translate a RNA message.
population Group of individuals of the same species living in the same area.
population density The size of the population within a particular unit of space.
population genetics Study of allele frequency distribution and change under the influence of evolutionary processes
positional information The molecular cues that control pattern formation.
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.
postsynaptic cell The neuron, muscle, or gland cell that receives the signal from a neuron.
postzygotic barriers Barriers that prevent the hybrid zygote from becoming a fertile adult.
potential energy Occurs when an object is not moving, but may still posses energy.
potential range An area where an organism could potentially survive and reproduce.
PR protein A protein involved in plant responses to pathogens (PR = pathogenesis-related).
pressure potential This measurement has a minimum value of 0 (when the solution is open to the environment); it increases as pressure increases.
presynaptic cell The transmitting neuron in a synapse.
prezygotic barriers Barriers that impede mating or hinder fertilization.
primary consumer Herbivore.
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.
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.
primary production Amount of light energy converted to chemical energy by autotrophs.
primary structure Chain of amino acids.
primary succession Succession that begins in a virtually lifeless area.
primary transcript The initial mRNA transcript that is transcribed from a protein coding gene. Also called pre-mRNA.
primase An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template.
producer Autotroph.
production efficiency The fraction of energy stored in food that was not used for cell respiration.
promiscuous No strong pair bonds or lasting relationships.
promoter A specific nucleotide sequence in DNA that binds RNA polymerase and indicates where to start transcribing mRNA.
prophage A phage genome that has been inserted into a specific site on the bacterial chromosome.
prostaglandins Modified fatty acids that are produced by a wide range of cells.
proteasomes A giant protein complex that recognizes and destroys proteins tagged for elimination by the small protein ubiquitin.
protein kinase The enzyme that transfers phosphate groups from ATP to protein.
protein phosphatases Enzymes that can rapidly remove phosphate groups from proteins.
protobionts Aggregates of abiotically produced molecules surrounded by a membrane.
proton pump An electrogenic pump that works largely with H+ ions.
proton-motive force Emphasizes the capacity of the gradient to preform work.
provirus Viral DNA that inserts into a host genome.
proximate questions Address environmental stimuli, genetic, physiological, and anatomical causes of a behavior.
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.
Punnett square A diagram for predicting the allele composition of offspring from a cross between individuals of known genetic makeup.
purines Bases with a double-ring structure.
pyramid of energy 90% of all energy is lost between trophic levels.
pyramids of biomass Each on this pyramid tier represents standing crop.
pyramids of numbers Number of organisms at each trophic level.
pyrimidines Bases with a single-ring structure.
quantitative characteristics Characteristics that vary along a continuum, usually due to influence of two or more genes.
quantitative characters Characters that vary in the population along a continuum (in gradations).
quaternary consumer Carnivore that eats tertiary consumers.
quaternary structure Results from two or more polypeptide subunits.
R plasmid A bacterial plasmid carrying genes that confer resistance to certain antibiotics.
r-selected species Life history traits maximize reproductive success in uncrowded environments. Many small offspring that mature quickly, little if any parental care.
radicle An embryonic root of a plant.
radioisotopes Isotopes that have unstable nuclei and undergo radioactive decay.
radiometric dating Dating using decay of radioactive isotopes.
random dispersion Random spacing of individuals of the same species within an area.
reaction center The location of the first light driven chemical reaction of photosynthesis.
reading frame Reading mRNA nucleotides in the correct groupings.
realized niche The niche species actually occupies.
receptacle The base of a flower; the part of the stem that is the site of attachment of the floral organs.
reception The target cell's detection of a signal molecule coming from outside the cell.
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.
receptor-mediated 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.
recessive allele An allele that is masked when a dominant allele is present
recombinant chromosomes Chromosomes that carry genes from each parent.
recombinant DNA A DNA molecule made in vitro with segments from different sources.
recombinant types Offspring who have inherited new combinations of genes and have phenotypes that don't match either parental phenotypes.
recticular formation Registers and controls activity level, increases excitement, and helps generate sleep.
redox reactions When there is a transfer of one or more electrons from one reactant to another.
reduced hybrid fertility Sterile hybrids due to uneven chromosome number.
reduced hybrid viability When the genes of different species interact and impair hybrid development.
reducing agent Donates electrons and becomes oxidized.
reduction Gain of electrons.
regulator An animal that uses internal control mechanisms to moderate internal change in the face of external fluctuation.
regulatory gene A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes.
relative abundance The proportion of each species.
relative fitness Fitness of a particular genotype.
repeated reproduction Species that reproduce over and over.
replication fork A Y-shaped region on a replicating DNA molecule where new strands are growing.
repolarization Return of the cell to resting state, caused by reentry of potassium into the cell while sodium exits the cell.
repressor A protein that suppresses the transcription of a gene.
reproductive cloning Using a somatic cell from a multicellular organism to make one or more genetically identical individuals.
reproductive isolation Barriers that impede members of two different species fro producing fertile offspring.
reproductive rate Difference between per capita birth and per capita death rates.
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.
resource partitioning Differentiation of niches that enables similar species to coexist.
response The transduced signal finally triggers a specific cellular response.
resting potential The membrane potential of a neuron that is at rest.
restoration ecology Applies ecological principles in an effort to return degraded ecosystems to conditions as similar as possible to their natural state.
restriction enzyme A degradative enzyme that recognizes and cuts up DNA (including that of certain phages) that is foreign to a bacterium.
restriction fragment The fragment of DNA that is produced by cleaving DNA with a restriction enzyme.
restriction fragment length polymorphisms (RFLPs) differences in the restriction sites on homologous chromosomes that result in different restriction fragment patterns.
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.
restriction site A specific sequence on a DNA strand that is recognized as a cut siteby a restriction enzyme.
reticular fibers Fibers made of collagen fibers that are very thin and branched. Forma tightly woven fabric that joins connective tissue to adjacent tissues.
retrovirus 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.
Created by: ssteuter