48. The quantity of eletrophoretic genotypes for the Mdh locus were found in a h

Question

48. The quantity of eletrophoretic genotypes for the Mdh locus were found in a human population. The numbers 1 and 2 in the table below represent two different alleles. Genotypes (numbers) 2/2 370 Locus 1/2 Mdh 620 10 Calculate the genotypic and allelic frequencies. a. b. Assuming random mating, calculate the expected number of heterozygotes at the Mdh locus c. Is this population in HWE at the Mdh locus? How could you tel1? d. What is one probable reason why the population would be out of HW based on the result?

Explanation / Answer

In the mentioned population in the question, there are two alleles - 1 and 2.

Total number of individuals in the population = 620+10+370 = 1000

Thus, three genotypes are possible from two alleles - 1/1, 1/2 and 2/2

a) Genotypic frequencies are calucated as follows:

For genotype 1/1, 620 / 1000 = 0.62

For genotype 1/2, 10 / 1000 = 0.01

For genotype 2/2, 370 / 1000 = 0.37

Allelic frequencies are calculated as follows:

1/1 humans will have two 1 alleles, 1/2 humans will have one 1 allele and 2/2 humans will have zero 1 allele.

So, the frequency of 1 allele = 0.62 + 0.5*0.01 = 0.62 + 0.005 = 0.625

And the frequency of 2 allele = 0.5*0.01 + 0.37 = 0.005 + 0.37 = 0.375

b) As per Hardy - Weinberg equation, p = frequency of 1 allele = 0.625 and q = frequency of 2 allele = 0.375

For calculating number of heterozygotes, first we need to calculate the frequency of heterzygotes = 2pq

= 2*0.625*0.375 = 0.46875

Now, the number of heterozygotes at mdh locus in a population of 1000 individuales, assuming random mating

= 1000*0.46875 = 468.75, that comes out approximately to 469

c) For a population to be in Hardy - Weinberg Equilibrium (HWE), p+q should be equal to 1.

Here, p+q = 0.625 + 0.375 =1. So, this population in in HWE.

d) Population would be out of Hardy-Weinberg Equilibrium, if its allelic frequency changes.

The probable reason this could happen is non-random mating or selection or migration.

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