AP Biology ALL VOCABULARY UNITS 1-8

Evolution

idea that living species are descendants of ancestral species that were different from present day ones; descent with modification

unity of life, diversity of life and how organisms are suited for life in their environments

Evolution explains the...

adaptations

inherited characteristics of organisms that enhance survival and reproduction in specific environments

natural selection

process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than do other individuals because of those traits

fitness

measure of reproductive success

genetic variation

differences among individuals in the composition of their genes

selective pressure

environmental conditions that 'select' some genetic variations with an advantage/increased fitness

microevolution

change in allele frequencies in a population over generations

genetic drift

process by which chance events cause allele frequencies to fluctuate unpredictably from one generation to the next

founder effect

when a few individuals become isolated from a larger population, a smaller group may establish a new population whose gene pool is different from the source population

bottleneck effect

when a population's size is greatly reduced, causing some alleles to be overrepresented, underrepresented, or absent

sexual selection

when individuals with certain inherited characteristics are more likely than other individuals of the same sex to mate

gene flow

transfer of alleles into our out of a population due to the movement of fertile individuals or their gametes

Hardy-Weinberg equilibrium

condition where allele frequencies remain constant between generations: large popuation, random mating, no mutations, no migration, no selection

allele frequency

number of one type of allele out of the total number of alleles in a gene pool

genotype frequency

number of individuals with one genotype out of the total number of individuals in a population

p

dominant allele frequency

q

recessive allele frequency

fossils

remains or traces of organisms from the past

strata

rock layers made by sediment settling then being compressed over millions of years

radiometric dating

process that can be used to figure out how old a fossil is because radioactive isotopes decay at a constant rate

half-life

time required for a parent isotope to decay

biogeography

study of the geographic distribution of species

endemic

native, or where a species evolved

homology

similarity resulting from common ancestry

homologous structures

structures that represent variations on a theme present in a common ancestor

vestigial structures

remnants of features that served a function in an organism's ancestors

antibiotic resistance

the ability of bacteria to withstand the effects of an antibiotic

endosymbiosis

theory that states organelles were formerly small prokaryotes that began living within larger cells

ongoing

so long as gene pools change over generations, environments change, then evolution is...

phylogeny

study of the evolutionary history of a species or a group of species

phylogenetic tree

branching diagram representing hypotheses about evolutionary relationships

branch points

divergence of two evolutionary lineages from a common ancestor, represents common ancestor of two groups

sister taxa

groups of organisms that share an immediate common ancestor; closest relatives

basal taxon

lineage that diverges from all other lineages early in the history of the group

analogy

similarity between organisms that is due to them encountering similar environmental pressures (not much genetic similarity)

cladisitics

methodology of classification that places species into groups that include an ancestral species and all of its descendants

cladogram

phylogenies based on homologous characteristics

outgroup

group that has diverged before the lineage that includes the species we study (group with least shared characters)

shared derived character

evolutionary novelty unique to a clade

clade

group of species that includes an ancestral species and all its descendants

speciation

process by which one species splits into two or more species

biological species concept (species)

a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

reproductive isolation

existence of biological barriers that impede members of two species from interbreeding and producing viable, fertile offspring

prezygotic barriers

block fertilization from occurring

habitat/geographic isolation

populations live in different habitats

temporal isolation

populations differ in breeding times

behavioral isolation

populations differ in mating rituals or other behaviors

mechanical isolation

populations are separated by body structure differences (morphology)

gametic isolation

populations are isolated due to incompatibility of sperm and egg

postzygotic barriers

prevent a hybrid zygote from developing into a viable, fertile adult

hybrids

offspring that result from interspecific (between species) mating

allopatric speciation

gene flow is interrupted when a population is divided into geographically isolated subpopulations

sympatric speciation

speciation between populations in the same geographic area

divergent evolution

evolution that occurs when adaptation to new habitats results in phenotypic diversification (species become more different over time)

punctuated equilibrium

long periods of little evolution occur, followed by sudden changes to species

gradualism

small evolutionary changes occur gradually over long periods of time

extinction

when a species no longer exists or cannot reproduce on their own

biodiversity

variety of living things and life processes

mass extinction

large number of species going extinct worldwide due to disruptive changes in global environments

Oparin-Haldane Hypothesis

Earth's early atmosphere allowed for organic compounds to form from simpler, inorganic compounds where energy came from lightning or UV radiation

Urey-Miller experiment

proved that complex organic molecules can form from inorganic compounds

montmorillonite

clay substrate that can catalyze nucleotides into RNA

protocell

droplets with membranes that maintained an internal chemistry different from that of their surroundings

RNA world hypothesis

states that RNA was the first genetic material; was able to self-replicate

ribozymes

RNA catalysts that allowed RNA to self-replicate if nucleotides were available

metabolism-first hypothesis

networks of chemical reactions in a protocell came before nucleic acids; reactions produced precursors to increasingly complex molecules

gene expression

process through which organisms use instructions in DNA to replicate DNA and direct RNA and protein synthesis

chromatin

condensed complex of DNA and proteins; circular in prokaryotes, multiple and linear in eukaryotes

plasmids

small circular DNA molecules that are replicated separately from chromosomes

polynucleotide

DNA and RNA; polymer consisted of many nucleotide monomers

pyrimidine

nucleotide whose nitrogenous base has one six-membered ring (C, T, and U)

purine

nucleotide whose nitrogenous base has a six-membered ring and a five-membered ring

antiparallel

strands of DNA are oriented in opposite directions (5' - 3' vs. 3' - 5')

semiconservative

method of DNA replication in which two daughter molecules will have one old parental strand and one newly made strand

helicase

enzyme that "unzips" DNA and opens the replication fork

replication fork

Y-shaped region on replicating DNA molecules

single-strand binding proteins

proteins that bind to unpaired DNA strands and prevent re-pairing of nucleotides

topoisomerase

stabilizes the double helix ahead of the replication fork

primase

enzyme that places the RNA primer on replicating DNA strands

primer

segment of RNA that serves as the starting point for replication by DNA polymerase

DNA polymerases

synthesize DNA by adding new nucleotides to the end of RNA primers

lagging strand

DNA strand elongating away from the replication fork due to DNA polymerase only synthesizing in the 5'-3' direction

Okazaki fragments

segments of DNA nucleotides and primers produced on the lagging strand

leading strand

DNA strand elongating toward the replication fork, continuously adding nucleotides; only needs one primer.

ligase

enzyme that joins the sugar-phosphate backbones of Okazaki fragments into one continuous strand

transcription

synthesis of RNA using information from DNA; RNA polymerases use a single template strand of DNA to direct inclusion of bases in new mRNA molecule;

messenger RNA (mRNA)

type of RNA that carries genetic message from DNA to the protein-making machinery of the cell

translation

synthesis of a polypeptide using the information in mRNA

ribosomes

sites of translation; molecular complexes that link amino acids into polypeptide chains

central dogma of molecular biology

genes program protein synthesis through genetic messages in the form of mRNA

template strand

strand of DNA that provides the pattern for the mRNA transcript

RNA polymerase

enzyme that pries two DNA strands apart, joins complementary RNA nucleotides and forms mRNA molecule

promoter

where RNA polymerase binds and initiates transcription

transcription factors

proteins that mediate the binding of RNA polymerase and initiation of transcription; form transcription initiation complex

terminator

DNA sequence that signals the end of transcription; detaches RNA polymerase from DNA (typically a poly-A tail)

primary RNA transcript

pre-mRNA; unprocessed mRNA before it exits the nucleus

5' cap

modified G nucleotide added to 5' end of primary RNA transcript

poly-A tail

50-250 A nucleotides that facilitate the export of mRNA from the nucleus on 3' end of primary RNA transcript

RNA splicing

removal of large portions of RNA and reconnection of remaining portions