Question

4. A pregnant woman is worried about the chances of her child having hemophilia as both she and her husband have paternal grandfathers with hemophilia. Neither their parents nor their maternal grandparents have hemophilia. Hint: use superscripts to label both normal and hemophilia genotypes.

What is the genotype of the paternal grandfathers who have hemophilia?

What is the genotype of their grandmothers and grandfathers without hemophilia?

Which of the pregnant couple’s parents could carry the gene for hemophilia?

Does (or can) either of the pregnant couple carry the gene for hemophilia?

What are the possible genotypes of the couple?

Do you think that the parents should worry about their child having hemophilia?

How would things change for the couple’s genotypes if their maternal grandfathers had hemophilia and their paternal ones didn’t?

Do you think that the parents should worry about their child having hemophilia?

5. In tomatoes, red fruit (R) is dominant to orange fruit (r). A homozygous red-fruited plant is bred to a orange-fruited plant.

1. What phenotypic ratio would you expect to see in the offspring (F1) of this cross?

2. If two of these offspring were bred, what phenotypic ratio would you expect to see in their offspring (F2)?

3. What genotypic ratio would you see in the F2 offspring?

Answer 1

let the alleles be X^H - normal X^h- hemophilia

the genotype of the paternal grandfathers with hemophilia is X^hY, the genotype of the maternal grandfathers without hemophilia is X^HY genotype of the grandmothers without hemophilia is X^HX^H

none of the pregnant couples parents will carry the allele for hemophilia. paternal grandfathers are affected with hemophilia, hemophilia is a sex-linked recessive disease and the males inherit their X chromosome from the mother, so here father of the woman and the man cannot inherit the X chromosome with the mutated allele on the X chromosome from their father`s.

NO. parents of both men and woman do not carry the allele for hemophilia so their children also do not carry the allele for hemophilia.

the genotype of the woman is X^HX^H and genotype of the man is X^HY

No. both man and woman does not inherit the allele for hemophilia, so they don`t have to worry about having a hemophilic child.

females inherit X chromosome from both father and mother, if the maternal grandfather was hemophilic, the mothers of man and the woman would be carriers of hemophilia, if the man is not hemophilic he does not carry the hemophilic allele from the mother but the woman can inherit the X chromosome with hemophilic allele from the mother. so possible genotypes of the woman is X^HX^H or X^HX^h and genotype of the man is X^HY, X^hY

yes. the woman can be a carrier of hemophilia, nothing is said about the phenotype of the man, if the man is hemophilic, both parents can have the allele for hemophilia then they can have hemophilic daughters as well as hemophilic sons.

if only the woman is hemophilia carrier and the man is normal they can have hemophilic sons.