ch 18 genetics terms

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amberd27
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ch 18 genetics terms
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2011-12-14 02:45:00
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biol 350 genetics terms
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  1. allele frequency
    proportion of alleles in a population of a particular type

    # of copies of allele x/ total # of alleles
  2. genotype frequency
    proportion of individuals in a population with a particular genotype
  3. Hardy_weinberg genotype frequencies
    • AA= p2
    • Aa= 2pq
    • aa= q2
  4. Hardy-Weingerg assumptions
    • Mutation is not occurring
    • Natural selection is not occurring
    • The population is infinitely large
    • All members of the population breed
    • All mating is totally random
    • Everyone produces the same number of offspring
    • There is no migration in or out of the population
  5. positive assortative mating
    bias of mating like with like; mate choice is dependent on resemblance to self. This is a source of reproductive isolation, as there is an excess of homozygotes at relevant loci
  6. negative assortative mating
    mating with unlike partners. Excess of heterozygotes at relevant loci
  7. inbreeding
    mating between relatives. Increases the probability of homozygosit at all loci. This can lead to a reduction in vigor and reproductive success, or inbreeding depression.
  8. inbreeding coefficient (F)
    the probability that two alleles in an individual trace back to the same copy in a common ancestor.
  9. mutation
    ultimate source of variability
  10. migration
    gene flow; creates genetic admixtures
  11. recombination
    generates new haplotypes and breaks down linkage disequilibrium
  12. genetic drift
    random changes in allele frequencies from generation to generation; due to finite size of real populations; decreases genetic variation
  13. founder effect
    genetic drift due to random sampling of a population to create a new population; many rare alleles are lost , whereas some rare alleles increase in frequency
  14. relative fitness
    relative contribution of an individual or genotypee to the next generation compared to another individual or genotype.
  15. directional selection
    frequency of an allele moves in one direction until lost or reaching fixation; decreases diversity
  16. positive selection
    increases frequency of beneficial alleles
  17. purifying selection
    eliminates deleterious alleles
  18. balancing selection
    maintains allele frequencies at an equilibriium point; maintains diversity when a heterozygous genotype is favored
  19. How do the following affect diversity?
    A) mutation
    B) migration
    C) recombination
    D) drift
    E) selection
    • A) increase genetic diversity
    • B) increase
    • C) increase haplotype diversity
    • D) reduced diversity (randomly)
    • E) either reduces or maintain diversity
  20. What are the forces that can change the frequency of an allele in a population?
    natural selection, mutation, migration, and genetic drift

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