Question

a. After several generations the actual genotype frequency for SCA in Nigeria is SS = 0.74, Ss = 0.24, and ss = 0.02. Calculate the frequency of allele “S” using the actual genotypic frequency for SCA in Nigeria. Enter to the 2nd decimal place

b. After several generations the actual genotype frequency for SCA in Nigeria is SS = 0.74, Ss = 0.24, and ss = 0.02. Calculate the frequency of allele “s” using the actual genotypic frequency for SCA in Nigeria. Enter to the 2nd decimal place.

Answer 1

Before answering the question, we can observe that the frequency of genotype in both the cases are same i.e.

SS=0.74 ,Ss= 0.24 , ss=0.02

Since after several generations also, the frequency of genotypes doesn't change,it means the population is in Hardy-weinberg equilibrium. So it can be calculated by using the equation

p² + 2pq + q²= 1

(a) The frequency of dominant genotype SS(p²)= 0.74

The frequency of dominant allele S(p)= √0.74 = 0.86 .

So, frequency of allele S in the population is 0.86 .

(b)

As we know this population is under HW equilibrium and the frequency remains the same even after several generations, we can apply another Hardy-weinberg equation to know the frequency of allele s in the population.

p + q = 1 where p and q are dominant and recessive allele respectively.

So frequency of recessive allele s(q)= 1- p

=> 1- 0.86 = 0.14

So the frequency of recessive allele s in the population is 0.14 .

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