meiosis

• Where does meiosis happen?

  In the reproductive organs (ovaries and testes) of organisms.
• What is the first step of meiosis?


  Before the cell starts to divide, it duplicates its genetic information, one arm of each chromosome is an exact copy of the other arm. After replication the chromosomes arrange into pairs.
• What happens during the 2nd step?

  The first division occurs and the pairs line up in the centre of the cell.
• What happens after the first division?

  The pairs are then pulled apart so each new cell only has one copy of each chromosome. Some of fathers and mothers go into each new cell.
• What happens in the 4th step?

  In the second division, the chromosomes line up again in the centre, the arms of the chromosomes are pulled apart.
• What happens after the second division?

  You get 4 gametes each with only a single set of chromosomes in it. Each of the gametes is genetically different from the others.
• Why are each of the gametes genetically different from the others?

  The chromosomes all get shuffled up during meiosis and each gamete only gets half of them, at random.
• meiosis half’s the number of chromosomes in gametes
• What happens after 2 gametes have fused during fertilisation?

  The resulting new cell divides by mitosis to make a copy of itself.
• As the embryo develops the cells then start to differentiate.