Question

If a hemophiliac Queen in the 17th century married a normal man (H= normal and h= hemophilia) What percent of their F2 generation sons would have the disease? What percent of their F2 generation daughters would be the carriers? What percent of their F2 children will be normal?
PLEASE EXPLAIN AND PROVIDE THE FORMULA IF POSSIBLE!!! THANK YOUUUUUU

Answer 1

Answer:

Hemophilia is a X-linked recessive disorder in which an organism looses its blood clotting properties or they are highly reduced.

It arises dues to the deficiency of clotting factors such as factor VIII and IX in the blood.

As it is X linked and a recessive disorder so a mother should be homozygous ($X^hX^h$) in order to have this disease while in males presence of single h ($X^hY$) can cause the disease as they are XY.

Females who carry only one copy of recessive gene ($X^hX^H$) are termed as carriers and they often show no sign of bleeding problems as they have one functional X.

Hence, the queen must be $X^hX^h$ and her husband must be $X^HY$.

The cross between the two would produce all carrier daughters ($X^hX^H$) and diseased sons ($X^hY$) in F₁ generation.

On selfing, they would produce two sons out of which one is diseased and two daughters out of which one is diseased and one is a carrier.

Hence, 50% of the F₂ generation sons would have the disease,

50% of the F₂ generation daughters would be the carrier of the disease.

So we can say that 50% of the F₂ generation is normal (carriers often lead a normal life).