This article waslast modified on 10 July 2017.
Threadlike structure in every cell nucleus that carries the inheritance factors (genes) composed of DNA (deoxyribonucleic acid, the gene material) and a protein (usually histone). A human cell normally contains 46 chromosomes, 22 similar pairs and 1 pair of sex chromosomes which are similar in girls but different in boys; one member of each pair of chromosomes is derived from each parent.