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How many chromosomes are there in a human body cell?

Chromosomes are thread-like strands of deoxyribonucleic acid (DNA) that carry the genes and transmit heredity information. A human being normally has 46 chromosomes (23 pairs) in all but the sex cells. Half of each chromosomal pair is inherited from the mother's egg; the other half, from the father's sperm. When the sperm and egg unite in fertilization, they create a single cell, or zygote, with 46 chromosomes. When cell division occurs (called mitosis), the 46 chromosomes are duplicated. This process is repeated billions of times over, with each of the cells containing the identical set of chromosomes.

Only the gametes, or sex cells, are different. In their cell division (called meiosis), the members of each pair of chromosomes are separated and distributed to different cells. Each gamete has only 23 chromosomes.

Chromosomes have thousands...

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