Last reviewed 01/2018

Chromosomes are strand-like structures within the nucleus of cells which represent discrete and highly structured collections of DNA.

In a somatic cell of a human, there are 46 chromosomes consisting of 23 pairs of chromosomes; each pair is made up of one maternal and one paternal chromosomal copy. There are 22 pairs of autosomes; they are virtually identical in appearance. The remaining pair of chromosomes are the sex chromosomes.

Each gamete cell has half the diploid complement of somatic cells i.e. 22 autosomes and one sex chromosome.