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Chromosomes.
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| Submitted: Mon Nov 17 2003
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Chromosomes * Most cells have a nucleus with a certain number of chromosomes. * There are twenty-three different pairs of chromosomes in human cells. * In females, each chromosome in the twenty-three pairs, appears to be identical to its partner. * In males, one pair is different, one chromosome is shorter than its partner. These two chromosomes are the sex chromosomes. * In females both the sex chromosomes are the same length. * We use an X to represent the longer sex chromosome and a Y to represent the shorter one. Fertilisation A woman has two X chromosomes, XX, while a man has one of each, XY. The two Xs or the X and Y are separated from each other during meiosis - the cell divisions that form sex cells or gametes. All healthy eggs produced by a human ovary have an X chromosome. However, with sperm, half carry an X...
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