Bio Exam 4

histones

histones

chromosomes consist of DNA wrapped around proteins called

loosely

Euchromatin is _____ packed

tightly

heterochromatin is _____ packed

antiparallel

DNA backbones are _____, meaning they run in opposite directions

origin of replication

when duplicating DNA, proteins first attach at the

DNA polymerase

synthesizes complementary DNA

helicase

Unwinds the DNA helix at the replication fork

binding proteins

keeps the DNA open during replication

topoisomerase

cuts, swivels, and repairs DNA ahead of replication form to relieve tension

RNA primer

allows new DNA to attach

primase

synthesizes complementary RNA primers

DNA poly I

removes RNA nucleotides and replaces them with DNA (added to 3’ end of fragment)

DNA poly III

uses parental DNA as a template and adds nucleotides to an RNA primer or existing DNA strand

5’ to 3’

new DNA strands are synthesized in the ___ order

ligase

repairs the gaps between Okazaki fragments

lagging strand

small strands synthesized then connected, moving away from replication fork

leading strand

one long DNA strand

mismatch repair

fixes damaged DNA by fixing replication errors

nucleotide excision repair

nuclease cuts out damaged part of DNA and repairs- no primer is needed

dna, rna, protein

gene expression order

gene expression

process by which DNA directs protein synthesis

transcription

synthesis of RNA using DNA

translation

synthesis of a polypeptide using mRNA info

ribosomes

sites of translation

nucleus

transcription takes place within the

cytoplasm

translation takes place within the

codon

composed of 3 nucleotides, codes for a protein, 64 possible

AUG

start codon, methianine

UAA, UAG, UGA

stop codons

sense strand

strand used for message/template

nonsense strand

doesn’t have message and therefore isn’t used

initiation, elongation, termination

order of transcription

AAUAAA

termination sequence for transcription

5’ cap

modified guanine nucleotide added to 5’ end of RNA

poly A tail

on 3’ end of RNA

x ray crystallography

evidence for double helix structure

spliceosome

looks for specific codes to cut out

protein domains

modular structure consisting of discrete regions of protein

transfer RNA

brings in amino acids during translation

initiation of translation

smal subunit attaches to mRNA

Large subunit completes initiation complex

elongation of translation

codon recognition

peptide bond forms

translocation- ribosome is ready for next aminoacyl t-RNA

termination of translation

ribosome reaches stop codon

release factor promotes hydrolysis

ribosome subunits and other units dissociate

point mutation

change of a single nucleotide in DNA template that can lead to an abnormal protein

missense

the point mutation results in the wrong amino acid being added

silent

no effect from the point mutation (ie same amino acid added)

nonsense

amino acid is changed to stop code

frameshift

deletion of insertion of a nucleotide results in a

mRNA

codons are a part of

mRNA, tRNA, rRNA

translation requires

trytophan

can be converted from other enzymes

repressible operon

operator

DNA “on-off” switch, usually within promoter

operon

entire stretch of DNA that includes operator, promoter, and genes

repressible operon

gene is turned on all the time unless inhibited

inducable operon

gene is only turned on when needed

inactive

in a repressible operon, the repressor is made in the ____ shape

active

in an inducable operon, the inducer is made in the _____ shape

negative

repressors are associated with (negative/positive) gene regulation

high

the lactose operon is likely to be transcribed when cAMP and lactose levels are _____

nucleosomes

consists of DNA and histones

epigenetic changes

DNA methylation and histone acetylation are examples of

control elements

segments of noncoding DNA

evolution

descent w/ modification

explains unity and diversity

endemic species

species found in one place

adaptation

increases survival and reproduction

natural selection

individuals with favorable traits are more likely to survive and reproduce

Darwin’s observations

populations vary in inherited traits

species have more offspring than the environment can support

Darwin’s inferences

individuals with more favorable traits reproduce more

more favorable traits gradually accumulate

population

the smallest unit of evolution

homologous structures

anatomical similarities

different function, same origin

evolutionary tree

makes hypothesis about relationships among different groups

convergent evolution

evolution of similar (analogous) structures independently from each other due to similar habitats

analogous

same structure/function, different origin

paleontology

study of fossils

microevolution

change in allele frequencies in a population over generations

genetic variation

caused by differences in genes or other segements

average heterozygosity

measure of average percent of gene loci that are heterozygous in a population

nucleotide variability

at a molecular level, _____ is examined

new genetic material

mutations are a source of

duplication

a small section of DNA is duplicated

fertile

a populations is a group of individuals in the same region capable of interbreeding and producing ______ offspring

gene pool

all alleles for all loci in a population

frequency adds to 1

not evolving

Hardy-weinberg equation can be used to calculate the genetic makeup of a population that is

constant

in hardy-weinberg equilibrium, allele frequencies remain _____ from generation to generation

genetic drift

unpredictable event that affects alleles available

founder effect

genetic drift in which a few individuals become separated from the rest

bottleneck effect

genetic drift in which environmental changes suddenly reduces the population

gene flow

immigration/emigration among populations

directional selection

one genotype/phenotype becomes more frequent in a population

disruptive selection

extremes are favored, and middle-type phenotype is less common

stabilizing selection

extremes become less common

sexual dimorphism

when you can tell male from female, results from sexual selection

intrasexual selection

direct competition among individuals of one sex for a mate

intersexual selection

individuals of one sex are choosy about who they mate

advantage

heterozygote ____ is where heterozygotes have a better fitness than either homozygote

frequency dependent selection

phenotype fitness declines if one phenotype becomes too common

speciation

origin of a new species

macroevolution

broad patterns of evolutionary change above the species level

biological species concept

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

reproductive isolation

biological factors that impede 2 species from producing viable or fertile offspring

prezygotic isolation

when fertilization between 2 species cannot occur