Final answer:
The ABO blood grouping is an example of multiple allelism and codominance. This is due to the presence of three alleles, IA, IB, and i, where IA and IB exhibit codominance when expressed together in the genotype IAIB.
Step-by-step explanation:
ABO Blood Grouping and Genetic Inheritance
The ABO blood grouping in humans is an example of multiple allelism and codominance. There are three alleles involved in the ABO blood group system: IA, IB, and i. The IA allele is responsible for type A blood group antigen, and IB for type B, while the i allele causes the type O blood group when it is in a homozygous state.
Both IA and IB are dominant over i, but when IA and IB are inherited together in a single individual (as in type AB), they express both A and B antigens equally on the red blood cells, which is why this case is an example of codominance, not incomplete dominance.
Each person has two alleles for the blood group gene, with the possibilities including IAIA, IAIO, IBIB, IBIO, and IOIO. Type AB blood is a result of an individual inheriting IA from one parent and IB from the other, denoted as IAIB. This unique situation shows that multiple alleles exist within the population, but a person only has two of these alleles, demonstrating a case of multiple allelism in Mendelian genetics.
The ABO blood grouping in humans is an example of multiple alleles. There are three alleles in the ABO blood type system (IA, IB, and i) that code for different antigens on red blood cells. The IA and IB alleles are codominant with each other and dominant over the i allele, resulting in four possible blood types: A, B, AB, and O.