Question: with respect to genetics abo blood types are controlled by...
With respect to genetics, ABO blood types are controlled by a single gene designated I, which has three alleles. The I A allele gives blood type A, I B gives blood type B, and i gives blood type O. The I A and I B alleles are codominant and i allele is recessive to both the I A and I B alleles.
Aside from the I alleles, there are two other genes that when mutated affect ABO blood type inheritance. The first mutant is recessive to wild type and is designated x. A homozygous xx individual is phenotypically O for blood type no matter what the genotype is of the I gene. For example, I A /I A x/x or I B /I B x/x individuals are O type. The second mutant, is dominant to the wild type Y allele and is designated Yd . An individual carrying a Yd allele is phenotypically blood type O no matter what the genotype is of the I gene. For example, an I A /I A Y/Yd or I B /I B Y/Yd individuals is O.
b. Propose a biochemical model that explains the phenotype of individuals carrying the dominant Yd mutant allele? This model must explain why this mutation is dominant to the wild type Y allele