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Genotype Frequencies

In a human population of 1000 people at a blood locus there are two alleles M and N. The observed genotype frequencies at this locus are f(MM) = 0.26, f(MN) = 0.35, and f(NN) = 0.39.

a. What is the frequency of each allele in this population? Do not assume Hardy-Weinberg equilibrium.

b. Based on the answer above calculate the expected frequencies of all genotypes at this locus assuming HW equilibrium.

Is the population in HW equilibrium? Explain your answer by doing a statistical analysis.

Give three criteria that must be fulfilled by a population, before it can be assumed it is in HW equilibrium? Explain why for each.

Solution Preview

The allele frequency refers to the frequency by which the individual allele (M vs. N) shows up.
The equation to determine allele frequency uses the genotypic frequencies of the homologus genes:

pM = f(MM) + 0.5[f(MN)] = 0.26 + 0.5(35) = 0.435

Similarly:

pN = f(NN) + 0.5[f(MN)] = 0.39 + 0.5(35) = 0.565 (or you could just do 1 - pM = pN since there are only two alleles)

The HW equilibrium assumes that:

p^2 + 2pq + q^2 = 1

where p = f(MM), q = f(NN) and 2pq = f(MN)

This essentially creates a mathematical model which predicts the general distribution of homozygous and heterzygous organisms, of which the ...

Solution Summary

The frequency of each allele in the populations are determined. Hardy-Weinberg equilibrium is analyzed.

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