Y chromosome: Encyclopedia II - Y chromosome - Function

Y chromosome - Function

Each person normally has one pair of sex chromosomes in each cell. As a general rule, the Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes. However there are exceptions where this is not the case, for details see Intersex. Many of the genes on the Y chromosome are involved in male sexual determination and development; the most important of them is the SRY gene, which seems to determine the sex in primates. (Other mammals may use a different gene.)

Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. The human Y chromosome likely contains between 70 and 300 genes versus more than 1000 genes for the X chromosome.

The human Y chromosome is unable to recombine with the X chromosome, except for small pieces on the ends, which comprise about 5% of the chromosome's length. About 56 of the Y chromosome genes are in this area and as a result are common between the two sex chromosomes.

Adapted from the Wikipedia article "Function", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki