chromosome
n. a strand or filament composed of nucleic acid (mainly DNA in humans) and proteins (see chromatin) that carries the genetic, or hereditary, traits of an individual. Located in the cell nucleus, chromosomes are visible, through a microscope, only during cell division. The normal human complement of chromosomes totals 46, or 23 pairs (44 autosomes and 2 sex chromosomes), which are believed to contain a total of 20,000 to 25,000 genes (see genome). Each parent contributes one chromosome to each pair, so a child receives half its chromosomes from its mother and half from its father. —chromosomal
adj.