karyotyping is done at which phase of cell cycle?

Discussion in 'Question Zone' started by guest2011, Aug 22, 2012.

  1. guest2011

    guest2011 Moderator

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    Karyotypes are prepared from mitotic cells that have been arrested in the metaphase or
    prometaphase portion of the cell cycle, when chromosomes assume their most condensed
    conformations . A variety of tissue types can be used as a source of these cells. For cancer
    diagnoses, typical specimens include tumor biopsies or bone marrow samples. For other
    diagnoses, karyotypes are often generated from peripheral blood specimens or a skin biopsy. For
    prenatal diagnosis , amniotic fluid or chorionic villus specimens are used as the source of cells.
    The process of generating a karyotype begins with the short-term culture of cells derived from a
    specimen. After a period of cell growth and multiplication, dividing cells are arrested in metaphase
    by addition of colchicine, which poisons the mitotic spindle. The cells are next treated with a
    hypotonic solution that causes their nuclei to swell and the cells to burst. The nuclei are then
    treated with a chemical fixative, dropped on a glass slide, and treated with various stains that
    reveal structural features of the chromosomes.

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