Question

Sickle-cell disease is the result of codominance in the alleles for hemoglobin. AA is normal hemoglobin, SS results in sickle-cell anemia in which all red blood cells are sickshaped, AS results in half of the red blood cells being normal and half being sickled. What genotypic ratio is expected in the offspring of a man that is heterozygous and awoman that has sickle cell anemia?1 AS: 1 SS1 AA: 1 SSAll ASAl SS

Answer 1

Let us first draw the Punnet square for this cross:

The genotypic ratio is 1 AS: 1 SS, i.e., there is one individual with AS genotype for every individual with SS genotype.