final Flashcards
ch 13
function of DNA polymerase during DNA replication
adds complementary bases to leading strand to synthesize new DNA strand
what is the role of single-stranded binding proteins in DNA replication
coat and stabilize single strands of DNA to prevent them from reforming double stranded DNA
function of topoisomerase in DNA replication
prevents the rest of DNA strand from being twisted
function of DNA ligase in DNA replication
seal nick between two lagging strand fragments during DNA replication
significance of mutations in DNA
source of phenotypic variation
what is evolution
change in genetic composition of populations over time
evolutionary theory
understanding and application of mechanisms of evolutionary change to biological problems
according to Darwin, what are the three major propositions of evolutionary change
- species change over time. 2. divergent species share a common ancestors and have diverged gradually
artificial selection
selective breeding of animals and plants by humans to increase the frequency of favored traits from one generation to next
gene flow
exchange of genes between populations through migration of individuals or movements of gametes that can change allele frequencies
genetic drift
random changes in allele frequencies from generation to generation as a result of chance processes especially in small populations
nonrandom mating
mating systems that produce changes in genotype frequencies but not in allele frequencies leading to evolutionary changes
condition required for a population to be at genetic equilibrium
no mutation, no selection among genotypes, no gene flow, infinite population size, random mating
polymorphism
presence of two or more variants of a character in same population, maintained by natural selection
natural selection description
differential survival and reproduction of individuals
population A = 2000 plants, and population B= 250. We most expect to see an INCREASE in the frequency of deleterious alleles in population____ due to ___
b; genetic drift.
smaller population= increase in frequency of harmful alleles, inversely proportional
45% of individuales with mutation survive hatchling, 58% without mutation survive. This mutations doesnt affect any other component of fitness. This is a _____ mutation.
deleterious; bc it is decreasing survival rate
beneficial mutation increases organism’s fitness
neutral mutation, no effect
deleterious, decreases.
a small population of sawflies that was once connected to a larger one but is now isolated is no longer experiencing:
gene flow; no migration into or out population
which statement about HW eq is true?
-assumes that individuals prefer to mate with individuales with certain genotypes
-applies only to populations in which there is gene flow
- assumes popiulation are small
-assumes selection is occuring
-explains why dominant alleles dont necessarily replace recessive alleles in a population
last one
A population of a copepod species faced predation from fish that preferred larger individuals, but smaller individuales were less likely to obtain sufficient resources to reproduce. The size of the copepods has remained stable over several generations. Most likely, the population is experiencing_____. If the fish predators were to increase in number, the population would most likely experience____.
stabilizing selection; directional selection for smaller size.
which mode of selection leads to a reduction in variation but no change in the mean
stabilizing selection
