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Ks4 cell division and fertilization

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  • Teacher Notes The correct order of the stages of mitosis is: 1. D , 2. F , 3. A , 4. G , 5. E , 6. C , 7. B , 8. H.
  • Teacher Notes The correct order of the stages of meiosis is: 1. E , 2. D , 3. G , 4. F , 5. A , 6. C , 7. H , 8. B.
  • Transcript

    • 1. KS4 Biology Cell Division and Fertilization1 of 29 © Boardworks Ltd 2004
    • 2. Contents Cell Division and Fertilization Introducing cell division What is mitosis? Chromosomes and fertilization What is meiosis? Mitosis or meiosis?2 of 29 © Boardworks Ltd 2004
    • 3. How many cells? An adult human is made up of about 50 billion cells. That’s 50 000 000 000 000 cells! Everyone started out as just one single cell. How does one cell become 50 million million?3 of 29 © Boardworks Ltd 2004
    • 4. Cell division New cells are produced by old cells dividing. Why are new cells needed?  Growth and repair of body cells.  Production of specialized sex cells. New cells are needed for two main reasons, so there are two different types of cell division… …mitosis and meiosis.4 of 29 © Boardworks Ltd 2004
    • 5. Cell division and genetic information Cells don’t just split in half when they divide. If they did, there wouldn’t be much of the cells left! It is essential that the genetic information carried in a cell is transferred to the new cells. Where is genetic information carried in a cell? When a cell divides how can this genetic information be transferred without any of it being lost?5 of 29 © Boardworks Ltd 2004
    • 6. Cell division and chromosomes Chromosomes in the nucleus carry the genetic information of a cell. Chromosomes must be accurately copied and passed on during cell division. This is important to make sure that no genetic information is lost. Knowing about chromosomes and what happens to them during cell division is the key to understanding the differences between mitosis and meiosis.6 of 29 © Boardworks Ltd 2004
    • 7. Contents Cell Division and Fertilization Introducing cell division What is mitosis? Chromosomes and fertilization What is meiosis? Mitosis or meiosis?7 of 29 © Boardworks Ltd 2004
    • 8. What is mitosis? Mitosis begins with a single cell. original How many chromosomes does cell this cell contain? First the cell makes a copy of each chromosome… …then it divides. cell division Each new cell has a full set of chromosomes and is identical to the original cell. 2 new cells8 of 29 © Boardworks Ltd 2004
    • 9. What is mitosis? Each new cell can keep on dividing by mitosis. Mitosis makes new cells for growth and repair in all living things. That’s how you get from one cell to 50 billion! Mitosis is also called copying division. What does this mean?9 of 29 © Boardworks Ltd 2004
    • 10. Mitosis activity10 of 29 © Boardworks Ltd 2004
    • 11. Mitosis animation11 of 29 © Boardworks Ltd 2004
    • 12. Mitosis summary How does mitosis turn one cell into two new cells?12 of 29 © Boardworks Ltd 2004
    • 13. Stages of mitosis activity13 of 29 © Boardworks Ltd 2004
    • 14. Contents Cell Division and Fertilization Introducing cell division What is mitosis? Chromosomes and fertilization What is meiosis? Mitosis or meiosis?14 of 29 © Boardworks Ltd 2004
    • 15. How many chromosomes? How many chromosomes are there in each new human body cell produced by mitosis? 46 chromosomes (23 matching pairs) How many chromosomes are there in human sex cells? 23 unpaired chromosomes 23 unpaired chromosomes15 of 29 © Boardworks Ltd 2004
    • 16. How many chromosomes? Human sex cells have a set of 23 unpaired chromosomes – that’s half the usual number. Sex cells in animals and plants follow the same rules.  They have half the usual number of chromosomes.  They have a complete set of single chromosomes. Why is this important for fertilization and reproduction?16 of 29 © Boardworks Ltd 2004
    • 17. Fertilization animation FLASH 6 – Fertilisation FLASH 2 – Mitosis drag & drop17 of 29 © Boardworks Ltd 2004
    • 18. Chromosomes and fertilization18 of 29 © Boardworks Ltd 2004
    • 19. Sex cells and cell division Sex cells have half the usual number of chromosomes. Why aren’t new sex cells produced by mitosis? Sex cells have to be produced by a special type of cell division. This is why there are two types of cell division. Sex cells are produced by meiosis. In which organs does meiosis take place?19 of 29 © Boardworks Ltd 2004
    • 20. Contents Cell Division and Fertilization Introducing cell division What is mitosis? Chromosomes and fertilization What is meiosis? Mitosis or meiosis?20 of 29 © Boardworks Ltd 2004
    • 21. What is meiosis? Meiosis begins with a single cell. original cell First the cell makes a copy of each chromosome. first Now, there are two stages division of cell division… second division How many chromosomes do the new cells have compared to the original? 4 new cells21 of 29 © Boardworks Ltd 2004
    • 22. What is meiosis? Meiosis produces four new sex cells with half the original number of chromosomes. In animals, meiosis produces ova in females and sperm cells in males. In plants, the gametes produced by meiosis are pollen grains and ovules. Mitosis is also called reduction division. What does this mean?22 of 29 © Boardworks Ltd 2004
    • 23. Meiosis activity23 of 29 © Boardworks Ltd 2004
    • 24. Meiosis animation24 of 29 © Boardworks Ltd 2004
    • 25. Meiosis summary How does meiosis turn one cell into four new sex cells?25 of 29 © Boardworks Ltd 2004
    • 26. Stages of meiosis activity26 of 29 © Boardworks Ltd 2004
    • 27. Contents Cell Division and Fertilization Introducing cell division What is mitosis? Chromosomes and fertilization What is meiosis? Mitosis or meiosis?27 of 29 © Boardworks Ltd 2004
    • 28. Mitosis or meiosis?28 of 29 © Boardworks Ltd 2004
    • 29. Who wants to have a million cells? FLASH 2 – Mitosis drag & drop29 of 29 © Boardworks Ltd 2004