noun, plural: sex chromosomes
A type of chromosome in the genome that is involved in the determination of the sex as well as the development of sexual characteristics in an organism. It occurs in pairs in somatic cells while singly in sex cells (gametes).
A somatic cell contains a genome comprised of paired chromosomes: the autosomes and sex chromosomes. In humans, there are two forms of sex chromosomes: the X chromosome and Y chromosome. A pair of X and Y results in a male while a combination of X and X results in a female. This XX/XY sex-determination system is one of the most familiar sex-determination systems and is applicable in human beings and most other mammals. In this system, the sex of an organism is determined by the sex chromosomes since these chromosomes bear the genes that control the development of reproductive organs and other sexual characteristics of an organism.