Entry courtesy of
The National Human Genome Research Institute (NHGRI)

Chromosome

One of the threadlike "packages" of genes and other DNA in the nucleus of a cell. Different kinds of organisms have different numbers of chromosomes. Humans have 23 pairs of chromosomes, 46 in all: 44 autosomes and two sex chromosomes. Each parent contributes one chromosome to each pair, so children get half of their chromosomes from their mothers and half from their fathers.

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Dr. Eric Green, of the National Human Genome Research Institute's Genome Technology Branch, defines chromosome.