Question

Consider an X-linked recessive disease such as hemophilia. If a woman with the disease had children with a man that does not have the disease, how would that affect their progeny?

Do a Punnett square and answer the questions (use X^h for disease alleles and X for normal).

A. What are the possible gametes for the mother? For the father?

B. What percentage of the female children would have the disease? ___________

C. What percentage of the female children would be carriers only?_______________

D. What percentage of the male children would have the disease?_________________

E. What if a woman that was a CARRIER only had children with a man that had the disease? Do a Punnett square for that mating.

F. What percentage of the female children would have the disease?________________

G. What percentage of the female children would be carriers only?___________________

H. What percentage of the male children would have the disease?_________________

Answer 1

Answer :

Cross : XhXh X XY

Offsprings : XhX, XhY, XhX, XhY

Punnett square :

	Xh	Xh
X	XhX	XhX
Y	XhY	XhY

A. Possible Gametes for the mother = Xh

And, possible Gametes for the father = X and Y

B. Percentage of the female children would have the disease = 0%

C. Percentage of the female children would be carrier only = 2/2 X 100 = 100%

D. Percentage of the male children would have the disease = 2/2 X 100 = 100%

E. Cross : XhX X XhY

Offspring : XhXh, XhY, XhX, XY

Punnett square :

	Xh	X
Xh	XhXh	XhX
Y	XhY	XY

F. Percentage of the female children would have the disease = 1/2 X100 = 50%

G. Percentage of the female children would be carrier = 1/2 X 100 = 50%

H. Percentage of the male children would have the disease = 1/2 X 100 = 50%