Question

Define codominance.

Hint:

Codominance differs from incomplete dominance. In codominance, traits appear together (AB blood group), while in incomplete dominance, traits blend (red × white flowers → pink flowers).

Answer 1

Codominance is a form of inheritance in which both alleles of a gene pair in a heterozygote are fully expressed, resulting in offspring with a phenotype that shows both traits simultaneously, without blending. Key Features: \[\begin{array}{rl} \bullet & \text{Neither allele is recessive.} \\ \bullet & \text{Both alleles contribute equally and independently to the phenotype.} \\ \bullet & \text{The traits appear side by side, not mixed.} \\ \end{array}\] Example:
- In humans, the ABO blood group system is a classic example. The alleles \(I^A\) and \(I^B\) are codominant. - A person with genotype \(I^A I^B\) has both A and B antigens expressed on red blood cells, leading to AB blood group.