Question

ABO blood typing uses 3 alleles. From your course notes answer the following two questions: Which two are dominant? _________ Write the two dominant allele genotypes, using the capital letter I, and then a superscript for each of them. ______________________ Which allele is recessive? __________ Write the genotype (letters) for the recessive trait, beginning with the lower case i. ____________.

Answer 1

Answer:

Dominant alleles: I^A and I^B

Two Dominant allele genotype: I^AI^A, I^BI^B and I^AI^B

Recessive allele: "i"

Recessive allele genotype= "ii"

Explanation:

The ABO blood typing is regulated by three alleles: I^A, I^B and i. Here, alleles I^B and I^A are dominant over the allele "i" while I^A and I^B exhibit codominance for each other. Since the allele "i" is recessive to the allele I^A, the genotypes "I^AI^A" and "I^A i" impart blood type A to the individual.

Similarly, the genotypes "I^BI^B" and "I^B i" impart the blood type B to the individual. The genotype "I^AI^B" gives blood type "AB". The allele “i” is expressed only in the homozygous state and the genotype "ii" makes the blood type "O".