Meiosis

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Meiosis
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Meiosis

• In the gamete (a.k.a. sex) cells
• Double division
• Maintaining the DNA, but reducing chromosome
  count to 23
• https//www.youtube.com/watch?vqCLmR9-YY7o

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Chromosomes

• Humans have a Chromosome count of 46 (or 23 pairs
  one set from dad, one from mom)
• When an egg joins a sperm the count must stay at
  46 to remain human
• So, the egg can only have 23 chromosomes, and the
  sperm can only have 23 chromosomes

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Ploidy

• The number of sets of chromosomes in a cell.
• 2n Diploid full set of chromosomes
• n Haploid half a full set of chromosomes
• Humans n 23 chromosomes
• 2(n) 46

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Stages of Meiosis

• Prophase 1
• Metaphase 1
• Anaphase 1
• Telophase 1
• Cytokensis 1

• Prophase 2
• Metaphase 2
• Anaphase 2
• Telophase 2
• Cytokensis

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Original Gamete Metaphase Anaphase
Telophase Cytokinesis
2 Daughter Cells Metaphase 2 Anaphase 2
Telophase 2 Cytokinesis 4 Gametes
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Mitosis Meiosis
4 stages 8 stages
Somatic cells Gamete cells
Produces 2 diploid cells Produces 4 haploid cells
Purpose Growth and repair Genetic continuity
46 chromosomes per daughter cell 23 chromosomes per daughter cell