Question

If a daughter expresses a sex-linked recessive gene, she inherited the trait from:

a) her mother

b) her father

c) both parents

d) neither parents.

can you show work using  the punnet square, thank you.

Answer 1

	Xh	Y
XH	XHXh	XHY
Xh	XhXh	XhY

As you can see in the table:-

a) XHXh is the gene of the mother who is a carrier of sex linked recessive gene. She has a normal gene and recessive gene(Xh).

b) XhY is the gene of the father who is a affected male having sex linked reccesive gene. Father has a reccesive gene and a no gene on Y chromosome cause it doesn't carrier sex linked genes.

c) XHXh is a daughter that is a carries of the reccesive gene.

d) XHY is a son that does not carry the reccesive gene.

e) XhY is a affected male showing the reccesive gene.

f) XhXh is the affected daughter expressing the reccesive gene.

To express a sex linked reccesive gene on a daughter both the gene on sex chromosome X must pe recessive type. In presence of a dominant gene the daughter becomes carrier only and does not express the gene.

Thus for a possibility of a daughter who expresses the sex linked recessive gene i.e. XhXh the daughter must receive recessive genes from both mother and father. In account to receive a reccesive gene the father must be a affected father from sex linked recessive gene and the mother must be a carrier of the disease or a diseased female having both reccesive genes. Even if father is healthy male then it will give only a dominant gene XH thus any daughter produce will be only a carrier and cannot express a reccesive gene.

Thus the correct option is C. both parents.

Thank you. Please provide a Thumbs up.