Determine the genotypes of the parents, if it is known that they have one healthy daughter
Determine the genotypes of the parents, if it is known that they have one healthy daughter, one daughter who is a carrier of the color blindness gene (d), one healthy and one sick son. The recessive gene for color blindness is localized on the X chromosome.
x (D) – normal vision, X (d) – color blindness. If the parents have a healthy daughter, a daughter who is a carrier of color blindness, as well as healthy and sick sons, then one of them is heterozygous (for example, the mother) and has the genotype X (D) X (d), and the father is X (D) Y.
Parents: (mother) X (D) X (d) × X (D) Y
Gametes: X (D) X (d) X (D) Y
Prospective offspring: X (D) X (D) daughter is healthy, X (D) X (d) daughter is a carrier of color blindness, X (D) Y is a healthy son, X (d) Y is a son of a color blind patient.