4. Create a Punnett square showing the offspring of a man who does not have hemophilia and a woman
whose father is a hemophiliac (Hint: You may need to create more than one square). Describe the
possible outcomes.

Can someone tell me how to do the punnet square for this question like for example bb*Bb how do I figure that out

Hi there!

This is quite complicated, as this is not mendelian genetics, instead, hemophilia is a sex-linked trait. It is a trait linked to the X chromosome and also recessive for females (as they have two X chromosomes) and for males, as they only have one X chromosome, if they have the gene on their one X chromosome, they have the disorder.

Thus, for the Punnett square, we first want to know the genotype of the woman whose father is a hemophiliac. We know that the father's X chromosome must be affected, written as .  He also has an unaffected Y chromosome, making his two sex chromosomes Y. For the mother, we can assume she isn't one, and her chromosomes are XX. We can cross these. The image of the cross is attached, and labelled as first cross.

We can see from this cross there are two different outcomes, one unaffected male, and one carrier female. We know this cross is looking for the genotype of the woman, thus, we know her genotype is a carrier, X. We can cross this with the genotype of the male, who we know doesn't have hemophilia, meaning his genotype is XY (remember that males are just if they have one gene, they have the disease, and if they don't, they don't). I've also attached an image of the cross, labelled as second cross.

We can see different outcomes for every box. The top left one is X, another carrier female. The top right is XX, an unaffected female who doesn't have the disease. The bottom left is Y, meaning an affected male. Finally, the bottom right is XY, an unaffected male.

Hope this helps!