Gene I interacts with gene D to determine the blood phenotypes of humans. Gene I is the gene for ABO blood phenotypes in humans, and includes three alleles: IA, IB and i. Gene D includes two alleles. Allele D is dominant over allele d. In individuals homozygous for the d allele, the A blood phenotype is not expressed, and those individuals are blood type B. [Side note: there is no such gene as gene D. This is a hypothetical question.] a. Describe the mode of inheritance of blood phenotypes in one or two sentences, using appropriate genetic terminology and accounting for both genes (I and D). b. What are the expected proportions (or ratios) of the four ABO blood phenotypes in the offspring if a double homozygous recessive O phenotype mother mates with a type A phenotype father who is homozygous for I but heterozygous for D? Show your work. c. What are the expected proportions (or ratios) of the four ABO blood phenotypes in the offspring if a double heterozygous A phenotype mother mates with a double heterozygous A phenotype father? Show your work.
Gene I interacts with gene D to determine the blood
gene for ABO blood phenotypes in humans, and includes three alleles: IA, IB and i. Gene
D includes two alleles. Allele D is dominant over allele d. In individuals homozygous
for the d allele, the A blood phenotype is not expressed, and those individuals are blood
type B. [Side note: there is no such gene as gene D. This is a hypothetical question.]
a. Describe the mode of inheritance of blood phenotypes in one or two sentences, using
appropriate genetic terminology and accounting for both genes (I and D).
b. What are the expected proportions (or ratios) of the four ABO blood phenotypes in
the offspring if a double homozygous recessive O phenotype mother mates with a type A
phenotype father who is homozygous for I but heterozygous for D? Show your work.
c. What are the expected proportions (or ratios) of the four ABO blood phenotypes in the
offspring if a double heterozygous A phenotype mother mates with a double
heterozygous A phenotype father? Show your work.
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