Male karyotype. Coloured image of a normal male karyotype (set of chromosomes). The presence of a X and a Y chromosome (lower right) show that this is a male, females have two X chromosomes. Humans have forty- six chromosomes, arranged into twenty- three pairs, in most cells of the body. Chromosomes are made up of very condensed deoxyribonucleic acid (DNA). DNA contains sections, called genes, which encode the body's genetic information. Genes determine each cell,s structure, function and behaviour.