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MEIOSIS

MEIOSIS. LINDA HEIDENRICH BIOLOGY. ALL ABOUT MEIOSIS. Occurs in sex organs (testes and ovaries) Cuts the chromosome number in half Has two stages: Meiosis I and Meiosis II Follows PMAT Entire process preceded by INTERPHASE and succeeded by CYTOKINESIS. PROPHASE I. Just like mitosis

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MEIOSIS

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  1. MEIOSIS LINDA HEIDENRICH BIOLOGY

  2. ALL ABOUT MEIOSIS • Occurs in sex organs (testes and ovaries) • Cuts the chromosome number in half • Has two stages: Meiosis I and Meiosis II • Follows PMAT • Entire process preceded by INTERPHASE and succeeded by CYTOKINESIS

  3. PROPHASE I • Just like mitosis • Nuclear envelope disintegrates • Chromosomes become visible and pair with homologous chromosomes to form a tetrad • Spindle fibers appear

  4. METAPHASE I • Homologous chromosomes align at the center of the cell • http://en.wikipedia.org/wiki/Meiosis

  5. ANAPHASE I • Homologous chromosomes move to opposite poles of the cell • http://en.wikipedia.org/wiki/Meiosis

  6. TELOPHASE I • Nuclear membranes reform • Spindle fibers disappear • DIFFERENCE: Chromosomes remain visible • http://en.wikipedia.org/wiki/Meiosis

  7. REVIEW: Prophase: Nuclear envelope disappears, spindle fibers form Metaphase: Chromosomes align in the center of the cell Anaphase: Sister chromatids separate to different poles of the cell Telophase: Nuclear envelope reforms, spindle fibers disappear, chromosomes become invisible MEIOSIS II (MITOSIS)

  8. NONDISJUNCTION • Term for what happens when homologous chromosomes or sister chromatids fail to split. • Leads to trisomy (extra chromosome) or monosomy (too few chromosomes) • http://en.wikipedia.org/wiki/Nondisjunction • http://en.wikipedia.org/wiki/Down_syndrome

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