1. Cell division LOs State another term for cell division
State what happens to the number of cells after cell division
State why cell division is important
State what happens to the number of chromosomes in each cell after cell division
State the effect of uncontrolled cell division
Describe the process of cell division (S4)
Solve cell division calculations (S4)

2. What is Cell Division?
Cell division is a process where one cell divides (or splits) into two identical cells.
It is also called Mitosis

3. Animal cell division

4. Cell Division in an Animal Cell 2 identical daughter cells
parent cell
Nucleus dividing in two
Cytoplasm Dividing in two
2 identical daughter cells

5. Plant cell division

6. Cell Division in a Plant Cell Parent Cell
Nuclear Division
Cytoplasm Dividing into 2 & cell wall forming
2 Identical daughter cells

7. Task
Use page 58 in the Standard grade textbook to label your diagrams!

8. Cell division LOs State another term for cell division
State what happens to the number of cells after cell division
State why cell division is important
State what happens to the number of chromosomes in each cell after cell division
State the effect of uncontrolled cell division

9. Why is cell division important?
Think / pair / share – 2 minutes!
Why is cell division important?

10. Growth: embryo development
1 cell at fertilisation
(zygote)
Adult has 50 to 100 trillion cells in total
Billions of cells (280 days)
100 cells (5 days)
Cells don’t get bigger, they just increase in number

11. Repair of tissue Dog X-ray showing a broken femur
New cells divide to repair the damaged tissue

12. Why is Cell division important?
Cell division is essential because it allows organisms to:
GROW by increasing the number of cells in the body and
REPAIR damaged tissues (e.g. cuts in skin, broken bones)
Artificial human ear growing in mice

13. Why is Cell division important?
Organisms such as salamanders and starfish can regenerate (renew) damaged tissues
Regeneration of a limb

14. Cell division LOs State another term for cell division
State what happens to the number of cells after cell division
State why cell division is important
State what happens to the number of chromosomes in each cell after cell division
State the effect of uncontrolled cell division

15. A human has 23 chromosome pairs
Counting chromosomes
Where do you find chromosomes?
What do chromosomes contain?
Remember: chromosomes are long strands of DNA found in every nucleus.
All organisms have a fixed number of chromosomes in their nuclei. These are organized into pairs (I.e. one from mum, one from dad)‏
A Chicken
An Indian Fern
A Chimpanzee
A human has 23 chromosome pairs
24 pairs
18 pairs
630 pairs

16. Counting chromosomes
If a parent cell has 2 chromosomes, how many chromosomes would each of the daughter cells have?
Let’s find out… see the chromosome demo…

17. Counting chromosomes This cell has 6 chromosomes.
Before a cell can divide it has to double all of its genetic information so it can divide it equally between the 2 new cells.
2 cells are made.
Each cell contains 6 chromosomes in the nucleus.
So the number of chromosomes stays the same.

18. Cell Division Key Questions
How many daughter cells are made at the END of cell division?
What does cell division do to the NUMBER of cells in an organism?
If a parent cell has 46 chromosomes, how many chromosomes will the daughter cells have?
What happens to the number of chromosomes in a daughter cell? 2
It increases the number of cells 46
It stays the same

19. Why do cells have to be identical?
New cells MUST have the ______ number of chromosomes as the _____ cell. Otherwise important genetic information would be _____ and the new cells would not receive the correct information to work properly.
SAME
original
LOST
Copy and complete!
Word Bank: original lost same

20. Cell division LOs State another term for cell division
State what happens to the number of cells after cell division
State why cell division is important
State what happens to the number of chromosomes in each cell after cell division
State the effect of uncontrolled cell division

21. Uncontrolled Cell Division
Cancer: Unregulated Cell Division - YouTube
Normal cell division
Cancerous cell division
Day 1
cells
Day 2
Day 3
Day 4
Day 5

22. What happens when cell division goes wrong?
Cell division is very strictly controlled by genes. However, if the gene that controls cell division is wrongly triggered then cell division can occur uncontrollably.
This means cells will continue to grow and grow and grow. This is cancer.
Uncontrolled growth of cells form a lump called a tumour.