Meiosis

• Meiosis


  1. Interphase

  2. Prophase I

  3. Metaphase I

  4. Anaphase I

  5. Telophase I

  6. Cytokinesis

  7. Prophase II

  8. Metaphase II

  9. Anaphase II

  10. Telophase II

  11. Cytokinesis
• Meiosis


  A process that contributes to genetic variety, makes sperm and egg cells (gametes)
• Mitosis


  Makes identical body cells like skin and stomach cells, important for growth and repair
• Humans have 46 chromosomes in most body cells
• Human sperm and egg cells have 23 chromosomes
• Reduction division


  Meiosis goes from 46 chromosomes to 23 chromosomes in the gametes
• Interphase


  Cell grows, replicates DNA, carries out processes before meiosis or mitosis starts
• During interphase, the 46 chromosomes replicate to 92 chromatids, but are still counted as 46 chromosomes
• Prophase I


  Chromosomes condense and line up in homologous pairs, crossing over occurs
• Metaphase I


  Homologous chromosome pairs line up in the middle of the cell
• Anaphase I


  Homologous chromosomes are pulled apart to opposite sides of the cell
• Telophase I


  Two new nuclei form, cell divides by cytokinesis
• Prophase II


  Chromosomes condense, spindle fibers form, but no crossing over
• Metaphase II


  Chromosomes line up in single file in the middle of the cell
• Anaphase II


  Sister chromatids are pulled apart to opposite sides of the cell
• Telophase II


  Four new nuclei form, cell divides by cytokinesis
• Meiosis in males produces sperm cells, in females produces egg cells
• Meiosis leads to genetic variety due to independent assortment and crossing over
• Nondisjunction, where chromosomes don't separate correctly, can lead to genetic disorders