Question

(a) Explain the phenomena of multiple allelism and co-dominance taking ABO blood group as an example.
(b) What is the phenotype of the following :
`(i)I^Ai`
(ii) `i i`

Answer 1

(a) Multiple allelism is the phenomenon of occurrence of a gene in more than two allelic forms on the same locus. In ABO blood group in humans one gene I has three alleles `I^A,I^B`,
`I^@//i`.
Co-dominance is the phenomenon in which both alleles express themselves when present together. We inherit any two alleles for the blood group. When the genotype is IAIB the individual has AB blood group since both 1“ and IB equally influence the formation of antigens A and B.
(b) (i) `I^A`-blood group-A
(ii) ii-blood group-O