Can you answer the following questions on Hemophilia?

Question

Given: Hemophilia is an X-linked receive (Xh). The allele for normal clotting is XH

Answer the following questions:

What is the genotype of a female carrier of hemophilia? What does it mean to be a carrier?

1. What is the genotype of a normal male?

2. What is the genotype of a male with hemophilia ?

3. Who can a male pass the gene for hemophilia on to?

4. Who can a female pass the gene for hemophilia on to?

5. What is the genotype for a female that has hemophilia?

6. Cross a female carrier of the disease with a normal male. What are the chances the offspring will have hemaphilia? What are the chances the offspring will be a carrier?

Answer 1

1.  XHXh

2.  Xh Y

3.  Females only.

4.  Either s*x

5.  XhXh--but these are extremely rare.

6.  50% of either s*x will carry the gene; 50% of sons will have hemophilia, 0% of daughters will have the disease.

Answer 2

The genotypes of a female carrier would be XHXh, if both X chromosomes presented the hemophilia gene then the female would be afflicted with hemophilia.

1. XHY

2. XhY, because there is no other X chromosome the recessive gene automatically presents its phenotype.

3. A male can only pass on the hemophilia gene to a daughter, because it is not associated with the Y chromosome and a mother can only give X chromosomes.

4. A female can pass the gene on to any gender.

5. XhXh, recessive genes only present the phenotype if the genotype is homozygous.

6. (XHXh) x (XHY) produces XHXH, XHY, XHXh, XhY. There is a 25% chance of one of the offspring will be afflicted with hemophilia. A 25% change of a carrier female.

Answer 3

ATP-Man and Mark S are correct on questions 1-6, however, the first two questions weren't answered.

The initial questions are:

What is the genotype of a female carrier of hemophilia?

XHXh

What does it mean to be a carrier?

It means you carry the allele for the disease (in this case hemophilia), and can pass on the allele for the disease to your offspring, but you do not exhibit the disease.

As for question 6, ATP-Man and Mark S are correct, but your question asked about the overall chance for the offspring, which can be inferred from their answers, but they didn't give the actual number in their answers.  The overall chance for the offspring to have hemophilia is 25% and the overall chance the offspring will be a carrier is also 25%.  Here is why:

Cross:  carrier female X(H)X(h)  x  X(H)Y normal male

Offspring can be (25% chance for each):

X(H)X(H), normal female

X(H)Y, normal male

X(H)X(h), carrier female

X(h)Y, hemophiliac male

So, you can see where their answers come from, that the probability is 50% that the males will have hemophilia and none of the females and the probability is that 50% of the females will be carriers and none of the males will be carriers.

Answer 4

1. What is the genotype of a normal male?  XHY

2. What is the genotype of a male with hemophilia ?XhY

3. Who can a male pass the gene for hemophilia on to?The female offspring.

4. Who can a female pass the gene for hemophilia on to? Both offspring

5. What is the genotype for a female that has hemophilia? XhXh

6. Cross a female carrier of the disease with a normal male.

XHXh   x  XHY

What are the chances the offspring will have hemaphilia?

zero chance for the females 50/50 for the males.

What are the chances the offspring will be a carrier?

50/50 for the females zero for the males