chromosomes

the rod-like structures, present in the nucleus of every body CELL , that carry the genetic information or GENES . Each human body cell contains 23 pairs of chromosomes, apart from the SPERM and ova (see OVUM ), half derived from the mother and half from the father. Each chromosome consists of a coiled double filament (double helix) of DNA , with genes carrying the genetic information arranged linearly along its length. The genes determine all the characteristics of each individual. Of the pairs of chromosomes, 22 are the same in males and females. The 23rd pair are the SEX CHROMOSOMES , and males have one X-CHROMOSOME and one Y-CHROMOSOME , whereas females have two X-chromosomes. See also SEX-LINKED INHERITANCE .