Final answer:
The genome copes with different numbers of X chromosomes through X inactivation, where one of the X chromosomes in female cells becomes inactive, forming a Barr body. This process balances gene expression across sexes and mitigates the impact of abnormalities like Klinefelter and Turner syndromes.
Step-by-step explanation:
The genome manages varying numbers of X chromosomes through a process known as X inactivation. This mechanism ensures that females, who have two X chromosomes, do not express double the genetic dosage compared to males, who have only one X chromosome, thereby maintaining a balance in gene expression from the X chromosome. During early development, one of the X chromosomes in each female cell condenses into a structure known as a Barr body, becoming inactive, and making the expression of genes from the X chromosome roughly equivalent to that in males. This inactivation is random and once established, it's passed on to all descendant cells.
In cases of sex chromosome nondisjunction, like Klinefelter syndrome (XXY) or Turner syndrome (XO), the same mechanism of X inactivation helps to limit the impact of having an abnormal number of X chromosomes on development and function. Although phenotypic effects such as developmental delays and sterility may arise, most individuals with these syndromes can still function because their bodies inactivate the excess X chromosomes or compensate for the lack thereof, although the single active X in Turner syndrome is insufficient for entirely normal development.