Ks4 cell division and fertilization
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1) The document discusses the two types of cell division: mitosis and meiosis. Mitosis produces new body cells for growth and repair through copying of chromosomes, while meiosis produces gametes like sperm and egg cells through reducing chromosome number. 2) Meiosis takes place in the gonads/sex organs and results in four gamete cells each with half the number of chromosomes as the original cell. 3) Fertilization occurs when gametes from each parent fuse, restoring the full chromosome number and allowing for reproduction.
Ks4 cell division and fertilization
- 1. © Boardworks Ltd 20041 of 29 KS4 Biology Cell Division and Fertilization
- 2. © Boardworks Ltd 20042 of 29 Cell Division and Fertilization Contents Introducing cell division What is mitosis? What is meiosis? Mitosis or meiosis? Chromosomes and fertilization
- 3. © Boardworks Ltd 20043 of 29 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?
- 4. © Boardworks Ltd 20044 of 29 Cell division 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… New cells are produced by old cells dividing. Why are new cells needed? …mitosis and meiosis.
- 5. © Boardworks Ltd 20045 of 29 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?
- 6. © Boardworks Ltd 20046 of 29 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.
- 7. © Boardworks Ltd 20047 of 29 Cell Division and Fertilization Contents Introducing cell division What is mitosis? What is meiosis? Mitosis or meiosis? Chromosomes and fertilization
- 8. © Boardworks Ltd 20048 of 29 What is mitosis? Each new cell has a full set of chromosomes and is identical to the original cell. Mitosis begins with a single cell. How many chromosomes does this cell contain? First the cell makes a copy of each chromosome… original cell cell division 2 new cells …then it divides.
- 9. © Boardworks Ltd 20049 of 29 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?
- 10. © Boardworks Ltd 200410 of 29 Mitosis activity
- 11. © Boardworks Ltd 200411 of 29 Mitosis animation
- 12. © Boardworks Ltd 200412 of 29 Mitosis summary How does mitosis turn one cell into two new cells?
- 13. © Boardworks Ltd 200413 of 29 Stages of mitosis activity
- 14. © Boardworks Ltd 200414 of 29 Cell Division and Fertilization Contents Introducing cell division What is mitosis? What is meiosis? Mitosis or meiosis? Chromosomes and fertilization
- 15. © Boardworks Ltd 200415 of 29 How many chromosomes? How many chromosomes are there in human sex cells? How many chromosomes are there in each new human body cell produced by mitosis? 46 chromosomes (23 matching pairs) 23 unpaired chromosomes 23 unpaired chromosomes
- 16. © Boardworks Ltd 200416 of 29 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?
- 17. © Boardworks Ltd 200417 of 29 Fertilization animation FLASH 6 – Fertilisation FLASH 2 – Mitosis drag & drop
- 18. © Boardworks Ltd 200418 of 29 Chromosomes and fertilization
- 19. © Boardworks Ltd 200419 of 29 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?
- 20. © Boardworks Ltd 200420 of 29 Cell Division and Fertilization Contents Introducing cell division What is mitosis? What is meiosis? Mitosis or meiosis? Chromosomes and fertilization
- 21. © Boardworks Ltd 200421 of 29 What is meiosis? Meiosis begins with a single cell. First the cell makes a copy of each chromosome. Now, there are two stages of cell division… original cell first division second division 4 new cells How many chromosomes do the new cells have compared to the original?
- 22. © Boardworks Ltd 200422 of 29 What is meiosis? Meiosis produces four new sex cells with half the original number of chromosomes. Mitosis is also called reduction division. What does this mean? In animals, meiosis produces ova in females and sperm cells in males. In plants, the gametes produced by meiosis are pollen grains and ovules.
- 23. © Boardworks Ltd 200423 of 29 Meiosis activity
- 24. © Boardworks Ltd 200424 of 29 Meiosis animation
- 25. © Boardworks Ltd 200425 of 29 Meiosis summary How does meiosis turn one cell into four new sex cells?
- 26. © Boardworks Ltd 200426 of 29 Stages of meiosis activity
- 27. © Boardworks Ltd 200427 of 29 Cell Division and Fertilization Contents Introducing cell division What is mitosis? What is meiosis? Mitosis or meiosis? Chromosomes and fertilization
- 28. © Boardworks Ltd 200428 of 29 Mitosis or meiosis?
- 29. © Boardworks Ltd 200429 of 29 Who wants to have a million cells? FLASH 2 – Mitosis drag & drop
Editor's Notes
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- #14: 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.
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- #27: 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.
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