mutations Flashcards
define mutations
changes in genetic make up
two types of mutations
point mutations and chromosomal mutations
four types of point mutations
silent mutations, missense mutation, nonsense mutation, and frameshift mutations
define silent mutation
do not alter protien or change amino acid
define missense mutation and 3 effects
mutation resultsin different amino acid in protein.
- neutral mutation (no effcet)
-negative mutation (change amino and altersl
-postive mutation(enhances protein)
define nonsense mutation
creates stop codon on mrna(stopping translation)
define frameshift mutation
add extra addition of nucleiotides or loss changing next codon list which changes all amino acids
define chromosomal mutations
changes in chromosomal structure or number
describe chromosomal mutations
starts Af= ABCD. Am= abcd
can turn to abBCcd=duplication
AD= deletion
can be Bf= EFGH and go to EFGHBC= translocation
can turn ACBD=inversion(which is no longer regulated=tumor)
define evolution
change in allelic frequency of a population overtime
darwing 5 observations when studying nature
- more indivi born in pop than will survive to reproduce
- most pop stay relatively constant in size overtime(1 +2 struggle for existence)
- indivi in pop vary by many heritable traits
4.some trait varients allow their possesers to be more successful at surviving + reproducing (3+4 differential reproductive success) - these trait varients will become more common in future generations (logical conclusion)
define evolution by natural selection
change in allelic frequency of a pop overtime due to differtial reproductive success w/i pop that is based on heritable variation
what does natural selection require
differential reproductive success and variation
where did variation come from(2 things)
mutations(point+chromosomal) sexual reproduction (crossing over+independent assortment)
define fittness
contribution to the genetic make up of future pop(ex: quanity of offspring, quality of offspring)(fittness shorthand)
4 modes of natural selection
stablizing selection, directional selection, disruptive selection, balancing selection
define stabilizing selection
NS acts to resist a change of allelic frequencies because mean phenotype is most fit. (no evo) (graph: y axis F, x axis R hump curve that gets taller bc middle best)
define directional selection
NS acts to move mean phenotype towards one extreme of the range bc that extreme is most fit.(change in enviroment) (graph: same hump but moves to one side instead of up)
define didtruptive selection
NS acts to create two or more genetically different forms in the pop bc mean phenotype is least fit(salmon ex)(graph: same hump but now it splits to both sides forming at least two humps)
define balancing selection
NS acts to maintain genetic diversity in pop by farming heterozygotes or rare phenotypes(scale-eating fish)
4 mechanisms for evolution other than NS
mutations, gene flow, genetic drift, and non random mating
define gene flow
movement of alleles into or out of a pop(immigration wolves)
define gentic drift
loss in genetic variation due to random events that prevent some individuals in pop from reproducing
2 phenomenon of genetic drift
gentic bottle neck and founders effect