Bio lab 3 notes Oct 31 2009

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Published on 24 Aug 2010
School
Department
Course
Bio lab 3
Population genetics
Evolution acts on population
A population is all the members of the same species that live in one loaction
Dvo[oÁt segregation of alleles ans independent assortment
Hardy-Weinberg equation t p2+2pq+q2=1
When there is no changes in the gene pool genetic equilibrium (allele freuqncies will not change from
generation to generation) will only occur if~
1. Population is large enough to be unaffected by random gene change (mutation and gene drift)
2. No gene flow (immigration or emigration)
3. No mutations occur or there is mutational equilibrium
4. Reprodution is random
5. Natural selection is not acting on a particular phenotype.
Cases in lab:
Case 1: random mating, no selection
Case 2: selection
Case 3: heterozygote advantage
Case 4: genetic drift t a change in allele frequency within a population that occurs porely as a result of
chance~
Genetic drift will cause polulation to lose their heterozygotes, and to become comprised entirely of
homozygous individuals.
Founder effect t only the alleles of the founding individuals are passed to next generation
Populations that are initially large and then are reduced dramatically in size are said to have passed
through a population bottleneck.
Mutation t a permanent change in the sequence of DNA
Although physcial abnormalities result from some kind of mutation, most of them have no effect
about the phenotype
Occur during the peocess of DNA replication t errors: substiturion of one nucleotide, insertion or
deletion of a nucleotide bas t point mutation
Chromosomal or structural mutation tsmall segment of DNA can be deleted, duplicated, inverted or
translated.
A gene is a region of DNA that is transcribed and/or reanslated into a product that has a particular
function.
Mutation usually has low happen rate
4 types of mutations:
1. Neutral mutation t have no effect on fitness t a mutation could occur in a region of the genome
that is not expression t change in DNA sequence maynot results in change in amino acid
because a certain amino acid can have more than one code
2. Deleterious mutation t negative effect on fitness
3. Lethal mutation t lead to the death of the individual
4. Benetifical mutation t v(]]v]À]µo[(]v
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Document Summary

A population is all the members of the same species that live in one loaction. Case 4: genetic drift j a change in allele frequency within a population that occurs porely as a result of chance~ Genetic drift will cause polulation to lose their heterozygotes, and to become comprised entirely of homozygous individuals. Founder effect j only the alleles of the founding individuals are passed to next generation. Populations that are initially large and then are reduced dramatically in size are said to have passed through a population bottleneck. Mutation j a permanent change in the sequence of dna. T although physcial abnormalities result from some kind of mutation, most of them have no effect about the phenotype. T occur during the peocess of dna replication j errors: substiturion of one nucleotide, insertion or deletion of a nucleotide bas j point mutation. Chromosomal or structural mutation jsmall segment of dna can be deleted, duplicated, inverted or translated.

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