chiasma

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chiasma (pl. chiasmata) In genetics, a cross-shaped structure forming the points of contact between non-sister chromatids of homologous chromosomes, first seen in the tetrads of the diplotene stage of meiotic prophase I. Chiasmata are thus the visible expression of crossing-over of genes. There are usually one or more chiasmata per chromosome per meiosis. See also BREAKAGE and REUNION.

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chiasma (pl. chiasmata) In genetics, a cross-shaped structure that forms the points of contact between non-sister chromatids of homologous chromosomes first seen in the tetrads of the diplotene stage of meiotic prophase. Chiasmata are thus the visible expression of crossing-over of genes. There are usually one or more chiasmata per chromosome per meiosis. See also BREAKAGE AND REUNION.

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chiasma (pl. chiasmata)The point at which paired homologous chromosomes remain in contact as they begin to separate during the first prophase of meiosis, forming a cross shape. A number of chiasmata can usually be identified and at these points crossing over occurs.

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