Question

What is Codominance? Explain with an example.

Answer 1

Codominance:

1. It occurs when both the alleles of a gene lack dominant and recessive relationships and both are observed phenotypically to the same degree.
2. The phenotypic effect of each allele is observable in the heterozygous condition.

Example:

1. The gene I is in charge of ABO blood types in humans.
2. Sugar polymers protrude from the surface of the plasma membrane of red blood cells, and the kind of sugar is controlled by gene I.
3. I^A, I^B, and I are the three alleles of the gene (I).
4. Alleles I^A and I^B create a slightly different type of sugar, whereas allele I produce no sugar at all.
5. The allele I^A is codominant with the allele I^B.
6. Both I^A and I^B are completely dominant to the allele I.
7. When a person has both I^A and I^B antigen on their surface, their blood type is AB.
8. AB blood type in humans is an example of codominance.
9. In AB blood type the phenotypic effect of both I^A and I^B alleles is observed.