Meiosis

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Meiosis
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Purpose of Meiosis

• Meiosis process of making egg and sperm cells
• Sexual Reproduction the production and fusion
  of sex cells
• Egg female sex cell
• Sperm male sex cell
• Diploid having two sets of chromosomes, body
  cells
• Haploid having one set of chromosomes, sex
  cells (also called gametes)

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Overall Process of Sexual Reproduction
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Meiosis
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Fertilization
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Meiosis
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Zygote
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• Meiosis has two separate sets of steps Meiosis
  I and Meiosis II

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Steps to Meiosis I

• Prophase I Tetrad forms (four part structure
  made of two sets of homologous chromosomes),
  Crossing over occurs (exchanged of genetic
  material)
• Metaphase I homologous chromosomes line up in
  the center
• Anaphase I Homologous chromosomes separate
• Telophase I Spindle fibers break down, 2 new
  cells formed

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Steps to Meiosis II

• Prophase II spindle fibers form in two new
  cells, fibers attached to sister chromatids.
• Metaphase II sister chromatids line up in
  center
• Anaphase II Sister chromatids separate
• Telophase II nuclei reform, 4 new cells

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Results of Meiosis

• Makes four new cells that are genetically
  different from each other and the parent cell
• Makes sex (gamete) cells
• Allows for sexual reproduction to be possible
• Maintains the chromosome number in organisms

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Problems that can occur during Meiosis

• Nondisjunction the failure of chromosomes to
  separate properly during Anaphase I or Anaphase
  II
• Leads to down syndrome, Turner syndrome,
  Klinefelters syndrome, etc.