A type of cell division that occurs in the ovaries and testes during the production of egg and sperm cells. During meiosis in humans, a cell containing 23 pairs of chromosomes (46 in total) divides to form 4 sperm or egg cells, each with 23 single chromosomes. First, the chromosomes are duplicated to produce 4 copies of each chromosome (92 in total). Matching pairs of chromosomes line up and exchange genetic material. The cell then divides twice to form 4 daughter cells, with each taking 1 copy of each chromosome. Egg and sperm cells therefore have only half the usual chromosome content of a body cell, so that each parent contributes half of the child’s genetic material. The exchange between chromosomes means that each daughter cell has a unique genetic make-up. (See also mitosis).
Meiosis |
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