Reproduction

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  • Created by: nuhaazhar
  • Created on: 17-09-16 08:06
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  • Reproduction
    • Asexual reproduction
      • Parent organisms divide by MITOSIS
        • Mitosis produces NEW CELLS that are IDENTICAL to each other, and to the parent cell
          • Steps of mitosis
            • 1. Parent cell
              • 2. Chrrmsms make identical copies of themselves
                • 3. They line up along the centre
                  • 4. They move apart
                    • 5. Two daughter cells form with identical chrms to the parent cell
      • Examples
        • Potatoes
        • Strawberries
        • Bacteria
    • Sexual reproduction
      • Egg (23) + Sperm (23) = Zygote (46)
        • Zygote contains chrmsms from both parents
          • All zygotes are DIPLOID
        • Combination of genes
        • Gametes are produced by the process of meiosis
          • All gametes are HAPLOID
          • Steps of meiosis
            • 1. Parent cell
              • 2. Chrmsms make identical copies of themselves
                • 3. Similar chrmsms pair up
                  • 4. Sections of DNA get swapped
                    • 5. Pairs of chrmsms divide
                      • 6. Chrmsms divide
      • Examples
        • Humans
        • Some animals
        • Some plants
    • In humans
      • Gametes production
        • Egg matures = an egg cell bursts out of the ovary and into the funnel at the end of the oviduct (OVULATION)
        • Sperm production is v sensitive to heat. Too hot = cells with not develop
      • Stages leading to implantation
        • 1. Ovulation
          • 2. Fertilisation. Fusion of nuclei of 2 gametes
            • 3. The zygote divides by mitosis
              • 4. A ball of cells is formed
                • 5. Cells in the ball keep dividing. Now called an embryo.
                  • 6. Implantation. Embryo sinks into soft lining of uterus. Placenta starts to form.
      • Birth
        • Muscles of uterus = contract to push baby out
        • Wall of the vagina = stretch to allow baby to be pushed through
        • Wall of cervix = dilates and become softer; wide enough for baby
      • The menstrual cycle
        • A follicle containing an egg develops. Uterus lining is prepared.
          • Ovulation. Fertilisation could take place.
            • Follicle turns into corpus luteum.
              • Menstruation. Not fertilised egg = thick uterus lining breaks down and is gradually lost through the vagina (period)

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