mutation, selection, gene flow, genetic drift, non-random mating Flashcards
evelyn jensen (22 cards)
what is mutation?
any change in the nucleotide sequences of an organism’s DNA
what are mutagens? name examples
any factor causing DNA damage resulting in a mutation
- heat
- radiation
what are synonymous/nonsynonymous mutations?
synonymous: the amino acid does no change
nonsynonymous: the aa changes
what does the rate of mutations depend on?
variation of mutations can vary…
- among regions of the genome
-> base composition
-> position on genome (centromeres vs chromosomes)
-> presence of epigenetic modifications
- among organisms
-> efficiency of DNA repair mechanisms
-> exposure to mutagens
describe the relationship between mutation rate and genome size
prokaryotes n viruses: antiproportional
- small genomes have higher mutation rates
- large genomes have lower mutation rates
multicellular organisms:
- larger genomes lead to higher mutation rates
what is an allele?
different form of a gene
what is a gene pool?
the sum of all copies of all alleles within a popuation
what enables tardigrades to survive in extreme conditions?
Dsup protein suppresses x-ray induced DNA damage by 40%
-> binds to nucleosomes and protects chromosomal DNA from hydroxyl radicals
when does selection occur?
a difference in the fitness (survival and/or reproduction) of individuals based on their phenotype
when does natural selection occur?
when the difference in fitness occurs due to conditions in the biotic and abiotic environment
why has the frequency of the melanistic form of a peppered moth decreases in recent years?
pollution as a result of the industrial revolution decreased, leaving surfaces less dark -> lighter surfaces were better for non-melanistic peppered moth
when does artificial selection occur?
when the difference in traits occurs due to human trait preference -> selective breeding
-> basis of crop n livestock improvement
-> development of breeds
what is sexual selection?
nonrandom mating: when individuals mate preferentially with particular individuals, rather than at random
why must organisms balance survival and reproduction?
if an individual survives, but fails to reproduce -> no fitness
what is adaptation?
a process by which members of a population become better adapted to their environment over time
what is migration?
the movement of individuals or gametes
what is gene flow?
migrants’ survival and reproduction
what is genetic drift?
random changes in allele frequencies from one gen to the next, caused by chance occurrences, not selection
how does genetic drift affect larger vs smaller populations?
impact on larger populations is more insignificant, as many more generations must be diminished before the allele is eliminated or fixed.
what is a population bottleneck?
when a population is dramatically reduced in size, by chance small number of survivors may not be representative of the og population
what is the founder effect?
when a population is started by a small number of individuals, they are unlikely to posses all alleles found in the gene pool of the source population
-> less variable than original
