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Biology LibreTexts

5.S: Pedigrees and Populations (Summary)

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    • Pedigree analysis can be used to determine the mode of inheritance of specific traits such as diseases. Loci can be X- or Y-linked or autosomal in location and alleles either dominant or recessive with respect to wild type.
    • If the mode of inheritance is known, a pedigree can be used to calculate the probability of inheritance of a particular genotype by an individual.
    • The frequencies of all alleles and genotypes remain unchanged through successive generations of a population in Hardy-Weinberg equilibrium.
    • Populations in true Hardy-Weinberg equilibrium have random mating, and no genetic drift, no migration, no mutation, and no selection with respect to the gene of interest.
    • The Hardy-Weinberg formula can be used to estimate allele and genotype frequencies given only limited information about a population.

    Key Terms

    Pedigree charts

    mode of inheritance

    genetic counseling

    incomplete penetrance

    variable expressivity




    autosomal dominant

    autosomal recessive

    X-linked dominant

    X-linked recessive

    Y-linked inheritance


    mitochondrial inheritance (mtDNA)


    product rule

    sum rule



    Hardy-Weinberg formula

    p2 + 2pq + q2=1

    Hardy-Weinberg equilibrium

    assortative mating

    random mating


    genetic drift

    Contributors and Attributions