Exam 3 Part 2 Flashcards Preview

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Flashcards in Exam 3 Part 2 Deck (23)
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population genetics

study of allele fequencies in a population

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gene pool

all alleles in a population

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why measure genetic variation?

genetic engineering
infer diversity in preparation for selective pressure
inheritance patterns
genetic counseling/disease probability
adaptation
history of interbreeding

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genotypic frequency

the proportion of a speciic genotype within a population
ranges from 0-1

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allelic frequency

prportion of an allele within a population

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Hardy-Weinberg Law

allows us to calculate allelic and genotypic frequencies in the absence of evolutionary forces

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Hary-Weinberg assumptions

no migration
infinitely large population
random mating
no mutation
no natural selection

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purpose of Hardy-weinberg

standard of comparison
predictor
control

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cline

gradient for allele grequencies that changes in a systematic way according to the physcial attributes of the environment

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genotypic variation measured in laboratory

measure gene product
examine nucleotide sequence directly (sequence it after PCR)
look for polymorphisms
visualized

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forces that change allele frequencies

mutation
natural selection
genetic drift
migration

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mutation

converts one allele to another
new allele may be neutral, detrimental, or adventageous

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natural selection

individuals with alleles that confer and advantage in the environemtn, produce more offspring on average than others in the population

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fitness

the relative reproductive ability of a genotype

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selective mating

most organisms do not mate randomly

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positive mating

similar phenotypes mate

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negative mating

oppostie phenotypes mate

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genetic drift

changes in allele frequecies due to random sampling in a population
reduce genetic diversity

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contributions to genetic drift

small population size
bottleneck
founder effect

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bottleneck

population is drastically reduced

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founder effect

when a population is established from a small number of breeding individuals

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migration

introduces or eliminates allelic frequencies

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gene flow

individual migrates and contributes their alleles ot the gene pool of the receptive population