Question

DNA from 100 unrelated people was amplified by PCR with allele specific primers, The PCR products were separated and visualized on the following gel. A specific fragment was found to correspond to each blood group allele, indicated on the left hand side. The number of individuals with each gel pattern is shown across the top. 7351-749, 18 Assuming random mating, what is the expected frequency of Type B blood? А 0.0025 0.070 C. 0.0725 D 0.25 E 0.05

Answer 1

Answer)

Given :

I^AI^A genotype individuals number - 7

I^AI^O genotype individuals number - 35

I^BI^B genotype individuals number - 1

I^BI^O genotype individuals number - 7

I^OI^O genotype individuals number - 49

I^AI^B genotype individuals number - 1

It has been asked to calculate B type blood group frequency. B type blood group will have genotype I^BI^B, I^BI^O.

step 1 ) Calculating the frequency of B allele in a population of 100 individuals :

Each individual carries two alleles for a gene. Therefore the population of 100 will have 200 alleles for a gene.

The number of B alleles among those 200 is :

I^BI^B genotype individuals number - 1----> 2 B alleles

I^BI^O genotype individuals number - 14----> 7 B alleles

I^AI^B genotype individuals number - 1 -----> 1B allele

In total 10 B alleles. frequency of B allele = 10/200 ------->0.05

step 2) calculating the frequency of O allele:

I^AI^O genotype individuals number - 35 -------> 35 O alleles

I^BI^O genotype individuals number - 7 ----------> 7 O alleles

I^OI^O genotype individuals number - 49 ----------> 96 O alleles

In total 140 O alleles. frequency of O allele = 140/200 ------->0.7

step 3) calculating the expected frequency of B type blood group  I^BI^B, I^BI^O.

Let's denote the frequencies of alleles A, B, O as p, q, r respectively.

These alleles combine to give the following phenotypic blood types:

AA and AO (type A),

BB and BO (type B),

AB (type AB),

and OO (type O).

Expected frequency of B blood group = q² + 2 x q x r

we know the frequency of B allele q = 0.05

we know the frequency of O allele r = 0.7

substituting the values,

Expected frequency of B blood group = (0.05)² + 2x 0.05 x 0.7

Expected frequency = 0.0025 + 0.07 ------> 0.0725

Therefore Option C is the correct answer.