Question

In mice, the Sry gene is located on the Y chromosome very close to one of the pseudoautosomal regions that pairs with the X chromosome during male meiosis. Given this information, propose a model to explain the generation of unusual males who have two X chromosomes (with a Sry-containing piece of the Y chromosome attached to one X chromosome).

Answer 1

The model showing the condition must represent a recombination between the X and Y chromosome during meiosis in male.

Step-by-step explanation:

In males, the sex chromosomes are X and Y, whereas, the females have XX chromosomes. When the X chromosome of males fuses with the female gamete it give rise to a female progeny.

The Sry gene is present on the Y chromosome. In some cases, the recombination between the X and Y chromosome during meiosis in males takes place and result in an X chromosome containing Sry gene. This Sry gene is responsible for the male characters and progeny carrying two X chromosomes, in which one has the Sry gene would have the male characters.

So, the in this case should represented the crossing over between the X and Y chromosomes in males and then passing of the Sry containing X chromosome to progeny.