The ABO blood system in humans is controlled by three alleles—IA, IB, and i—resulting in four possible blood types. Codominance occurs in the AB blood type, where both A and B antigens are equally expressed, while IA and IB are dominant over i.
The ABO blood system is an intriguing example of multiple allelism and codominance in human genetics. The ABO blood group system is determined by three alleles: IA, IB, and i. These alleles are located on chromosome 9 and contribute to the formation of distinct blood types. The IA allele is responsible for A antigens on red blood cells, IB for B antigens, and the i allele does not produce any antigen, leading to type O blood.
Each person inherits two alleles, one from each parent, forming genotypes such as IAIA, IAi, IBIB, IBi, IAIB, or ii. The IA and IB alleles display codominance when inherited together, resulting in type AB blood where both A and B antigens are equally expressed. Conversely, both IA and IB alleles are dominant over the i allele.
An example of genotypic combination is seen when a heterozyous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate; there is a 25% chance that any of their offspring will inherit the IAIB genotype, expressing an AB blood type.
Question is incomplete the complete question is
Explain how In humans, the blood type trait is controlled by multiple alleles.