. A normal vision male marries a female who is a carrier of the color-blind gene and she becomes pregnant. What will a genetic counselor tell the parents regarding the a) percentage of having a daughter who is color-blind; b) what is the percentage of having a son who is color-blind? Consider a different couple with a female with normal vision and a male with normal vision. Would it be possible for their daughter to be a carrier for color-blindness? Explain your answer.

Explanation:

a, The genetic counselor should  explain that color-blindness is a sex-linked disorder, that is its  expression is related to a particular sex-cells.

a) The percentage is 0% . This is because your husband is normal, so no sex-linked alleleis attached to his only X-chromosomes.However either of your X-chromosomes can bear the allele for color blind. Since a girl child sex-chromosomes combination is XX, and your husband X chromosomes is normal,hence your daughters can only be carries (XCX, XCX)like you  if they inherited any of your X -chromosomes color blind allele.But none will be colorblind.

b)Because you are carrier for this alllele, and your husband is normal;  chances are all your sons   be   colourblind  is 50% proportion(YXC/YXC).  This is because your husband Y chromosomes determines a male child, and you can  bear the defective(carrier allele)  for  colourblind  on either of your X-chromosmes to give a male child as XY. Thus either of the  male child  assuming  with Mendelian fashion of inheritance, will be colour blind in 50% proportion.

No. A girl child can only be  a carrier for color blindness  if the  inherited the color blind gene from her carrier mother  or the father is color-blind. None of this is present in this scenario.  The two parents are normal Therefore there is no chance of their daughter emerging a carrier.

a- all cells come from pre-existing cells