MEIOSIS

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MEIOSIS

• Reduction-Division
• Genetic Recombination

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Meiosis

• The form of cell division by which GAMETES, with
  HALF the number of CHROMOSOMES, are produced.
• DIPLOID (2n) ? HAPLOID (n)
• Meiosis is SEXUAL reproduction.
• TWO divisions (MEIOSIS I and MEIOSIS II).

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Meiosis

• Sex cells divide to produce GAMETES (sperm or
  egg).
• Gametes have HALF the of chromosomes.

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Spermatogenesis
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Interphase

• Similar to mitosis interphase.
• CHROMOSOMES (DNA) replicate
• Each duplicated chromosome consist of two
  identical SISTER CHROMATIDS attached at their
  CENTROMERES.
• ONLY occurs during meiosis I

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Meiosis I (four phases)

• Cell division that reduces the chromosome number
  by one-half.
• Cell division in which
• chromosomes go though same stages as mitosis.
• Four phases
• a. Prophase I
• b. Metaphase I
• c. Anaphase I
• d. Telophase I

Prophase I
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MEIOSIS I
Chromosome 3 (two copies)
Meiosis I

• Homologous pairs of chromosomes separate

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MEIOSIS II

• Sister Chromatids Separate

Meiosis II
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Meiosis II

• No Interphase II
• No DNA Replication
• Four phases to divide sister chromatids.

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The outcome

• Remember FOUR HAPLOID DAUGHTER cells are
  produced.
• Called GAMETES (eggs and sperm)

1n Sperm cell fertilizes 1n egg to form 2n zygote
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