Scientists believe that the Y chromosome is one of the fastest evolving pieces of genetic material in humans with a 30% difference in humans and primates. It contains somewhere between 70 and 200 genes, which they are actively working on identifying. While the Y chromosome does contain genes that are only found on this one chromosome, there are areas that have pseudoautosomal genes (an autosomal chromosome is a non sex determining chromosome), which means they are found on both the X and Y chromosome.
There are diseases that can be associated with the Y chromosome, such as 46,XX where a male will have two X chromosomes and one Y, 48,XXYY where he will have double of both sex chromosomes, and 47,XYY where he will have two copies of the Y chromosome. These can have symptoms anywhere from a tall stature to infertility.
I can't believe this is the second to last post for the A to Z Challenge. I hope everyone has learned at least one thing from my posts!