1· A man who has color blindness and type O blood has children with a woman who

Question

1· A man who has color blindness and type O blood has children with a woman who has normal color vision and type AB blood. The woman's father had color blindness. Color blindness is determined by an X-linked gene, and blood type is determined by an autosomal gene. a. What are the genotypes of the man and the woman? b. Show the Punnett square for a cross between this man and woman, showing all possible genotypes of the children c. What proportion of their children will be color blind and type B blood? . What proportion of their children will be color blind and type A blood? e. What proportion of their children will be color blind and have type AB blood?

Explanation / Answer

1 a). Since the man is color blind therefore his genotype will be XrY, since this is an X-linked recessive disorder, so only the presence of recessive gene can lead to the disease. Therefore, he is hemizygous. Also, since his blood group is O, therefore he is homozygous for the ‘O’ allele. Therefore his exact genotype is (IOIO) XrY.

The female has normal vision, but her father had color blindness. Since all females receive one copy of the X-chromosome from the father, therefore she is hetrogygous XRXr. Also, she has AB blood group which means she has the ‘A’ and ‘B’ alleles present. Therefore her genotype would be (IAIB) XRXr.

b).

(IO) Xr

(IO)Y

(IAIB) XR

(IAIO) XR Xr or (IBIO) XR Xr

Normal, A or B blood group

(IAIO) XR Y or (IBIO) XR Y

Normal, A or B blood group

(IAIB) Xr

(IAIO) Xr Xr or (IBIO) Xr Xr

Colorblind, A or B blood group

(IAIO) Xr Y or (IBIO) Xr Y

Colorblind, A or B blood group

c). As can be seen above in the Punett squae out of 4 children, 2 will be colorblind with type-B blood group, i.e., 2/4= 0.5.

d). As can be seen above in the Punett squae out of 4 children, 2 will be colorblind with type-A blood group, i.e., 2/4= 0.5.

e). None of the children will be colorblind with type AB blood group as the father has only O antigen therefore the children can be either A or B.

(IO) Xr

(IO)Y

(IAIB) XR

(IAIO) XR Xr or (IBIO) XR Xr

Normal, A or B blood group

(IAIO) XR Y or (IBIO) XR Y

Normal, A or B blood group

(IAIB) Xr

(IAIO) Xr Xr or (IBIO) Xr Xr

Colorblind, A or B blood group

(IAIO) Xr Y or (IBIO) Xr Y

Colorblind, A or B blood group

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.