Meiosis and Fertilisation

• Meiosis


  The process by which gametes (sperm and egg cells) are produced, with half the normal number of chromosomes
• Chromosomes in normal human cells

  • 23 pairs
• Chromosomes in gametes


  • Single, not paired
• Meiosis


  1. Chromosomes are copied

  2. Cell divides into two

  3. Both cells divide one more time forming gametes
• Meiosis produces four gametes from one original cell, and each gamete is genetically different</b>
• Fertilization


  The joining of a male gamete (sperm) and a female gamete (egg) to form a new cell with the full number of chromosomes
• After fertilization, the new cell has 23 chromosome pairs
• After fertilization


  1. New cell divides by mitosis

  2. Produces a clump of identical cells (embryo)

  3. Cells differentiate to form different cell types