SEX CHROMOSOMES

=Sex Chromosomes= [image:http://i.imgur.com/9J5O0lE.png] The sex of an individual is determined by two sex chromosomes. Males have an X and a Y chromosome (XY). Females have two X chromosomes (XX). =Sex determination= When a female (XX) produces gametes, the egg always contains an X chromosome. Males (XY) produce sperm cells with either an X or a Y chromosome. The sex of an individual is determined by which sperm fertilises the egg. If a sperm cell carrying a Y chromosome fertilises the egg, the child will be male (XY). If a sperm cell carrying an X chromosome fertilises the egg, the child will be female (XX). [image:http://i.imgur.com/JoCzVS3.png] Note the other chromosomes have not been shown here for simplicity