In mice, the Sry gene (see Section 5.2) 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 an Sry-containing piece of the Y chromosome attached to one X chromosome).

Question: Explain the generation of unusual males with two X chromosomes, where one of them has an Sry-containing piece of the Y chromosome attached. Answer: The generation of unusual males with two X chromosomes occurs due to a rare recombination event during meiosis in the parent. In this event, the Sry gene, which is usually located on the Y chromosome, gets transferred to the X chromosome. As a result, individuals with an X chromosome from the mother and an X' chromosome (X chromosome with Sry gene) from the father would be genotypically XX, but still possess the Sry gene, causing them to develop male characteristics. This leads to unusual males with two X chromosomes, where one of the X chromosomes has an Sry-containing piece of the Y chromosome attached.