As discussed previously, the ABO locus in humans has three alleles, where IAand IBare co-dominant and i is recessive to each. Suppose that, in a large population at equilibrium, the frequency of the IA allele is 0.35 and the frequency of the IB allele is 0.15.

a. What is the expected frequency of people with type AB blood in this population?

b. What is the expected frequency of people with type A blood?

c. A blood bank collects 5000 pints of blood during a blood drive and finds that 1850 were type A, 635 were type B, 180 were type AB and 2335 were type O. Calculate the frequencies of the IA, IB, and i alleles in this population. (Hint: you should first determine the iallele frequency.

using the formula p² + 2pq + 2pr + q² + 2qr + r² = 1 where p is IA allele is 0.35 and q is IB allele is 0.15.

Thus, the expected frequency of people with type AB blood in this population will be (2pq) = 2 x 0.35 x 0.15 = 0.105

b. The expected frequency of people with type A blood will be p² + 2pr = where r is found using the formular p + q + r = 1 = 1 - (p+q) = 1 - (0.35+0.15) = 0.5

Thus, we have the expected frequency of people with type A blood to be (0.35² + 2x0.35x0.5) = 0.4725.

c. p² + 2pr + 2pq + q² + 2qr + r²

AA AO AB BB BO OO

1850 180 635 2335

frequency of IA - p = (1850 + 180/2) / 5000 = 0.388

frequency of IB - q = (635 + 180/2) / 5000 = 0.145

frequency of i - r = 2335 / 5000 = 0.467.

since r² = 2335, r = √2335 = 48.32

using the formula p + q + r = 1