Answer:
- the allelic frequency for p is 0.967
- the allelic frequency for q is 0.033
Explanation:
According to Hardy-Weinberg, the allelic frequencies in a locus are represented as p and q, referring to the alleles. The genotypic frequencies after one generation are p² (Homozygous for allele p), 2pq (Heterozygous), q² (Homozygous for the allele q). Populations in H-W equilibrium will get the same allelic frequencies generation after generation. The sum of these allelic frequencies equals 1, this is p + q = 1.
In the exposed example,
- A recessive genetic disorder is fatal before birth, so there are no homozygous recessive individuals
- In a particular population, one in 15 individuals is a carrier for this disorder.
What are the allele frequencies of the dominant (p) and recessive (q) alleles in this population?
If 1 of 15 individuals are carriers for this disorder, this means that 1/15 are heterozygous, 2pq. So, 2pq = 1/15 = 0.066
Now we must calculate the allelic frequencies.
We know that 1 in 15 individuals are heterozygous, and we also know that there are no recessive homozygous, q², because they can not survive, so of the 15 individuals only one is heterozygous and the rest 14 individuals must be dominant homozygous, p².
The dominant homozygous genotypic frequency is
p²= 14/15 = 0.933
And by clearing the next equation we can get the allelic frequency for p
p²= 0.933
p = √0.933
p = 0.967
So now we know that the allelic frequency for p is 0.967
This means that the allelic frequency for q or p is 0.033, which we deduce by clearing the equation p + q = 1
0.967 + q = 1
q = 1 - 0.967
q = 0.033
- the allelic frequency for p is 0.967
- the allelic frequency for q is 0.033
