1. Mitosis and Cell Division

2. Three reasons why cells reproduce by asexual reproduction: 1. Growth 2
Three reasons why cells reproduce by asexual reproduction: Growth Repair Replacement
Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun.
Cell that reproduce by asexual reproduction reproduce constantly.

3. Cell division
All complex organisms originated from a single fertilized egg.
Every cell in your body started here, through cell division the numbers are increased
Cell then specialise and change into their various roles

4. Parent cell
Chromosomes are copied and double in number
Chromosomes now split
2 daughter cells identical to original

5. Mitosis
All daughter cells contain the same genetic information from the original parent cell from which it was copied.
Every different type cell in your body contains the same genes, but only some act to make the cells specialise – e.g. into nerve or muscle tissue.

6. Stages of Cell Division
1. Interphase
2. Mitosis
Prophase
Metaphase
Anaphase
Telophase
3. Cytokinesis

7. Interphase 1. DNA replication
2. Centrioles duplicate (animal cells only)

8. Prophase
Chromatin condenses into double stranded chromosomes joined by a centromere
Nuclear membrane dissolves freeing the DNA
Spindle fibers stretch across the cell from centrioles that have moved to opposite ends of the cell

9. Metaphase
Tugging action of the spindle fibers pulls the double stranded chromosomes into a line across the middle of the cell
Highly organized so that both new cells will get exactly the same DNA

10. Anaphase Spindle fibers begin to contract and shorten
This action pulls the centomere apart, allowing one of each of the replicated chromosomes to move to opposite ends (poles) of the cell.

11. Telophase
One complete set of chromosomes is now at each pole of the cell
Nuclear membrane forms around each set of chromosomes
Chromosomes uncoil into chromatin
Cytokinesis begins

12. Cytokinesis
Division of all the rest of the cell’s organelles into two identical daughter cells.
Animal Cells: A cleavage furrow pinches off the cell.
Plants Cells: A cell plate develops across the centre of the cell, forming a new cell wall

13. Mitosis – animal bone cells2 1
Cells split
Chromosomes copied
Parent cell 3 4 5
2 daughter cells
Copies separating

14. Plants apical meristem

15. Rat – epithelial cells

16. Cancer … cell cycle gone wrong
What is cancer?
Cancer is essentially a disease of mitosis
The normal 'checkpoints' regulating mitosis are ignored or overridden by the cancer cell.
Cancer begins when a normal single cell is transformed into a cancer cell.
Often this is because of a DNA mutation that occurs in one of the genes that normally controls growth.
Once these crucial Cell Cycle genes start behaving abnormally, cancer cells start to proliferate wildly by repeated, uncontrolled mitosis

17. Cancer Growth Animation Worksheet
View the cancer growth animation using the following url:
Answer the following questions from the animation
1. What type of cancer is studied in the animation and where does it form?
2. How many cells are in the human body?
3. Identify two things that can cause mutation?
4. Why do normal cells usually reproduce?
5. What is angiogenesis?
6. What is metastasis?