1. Why do cells divide? Populations of single-cell critters
Multicellularity
We all start out as a single cell…a zygote
& become/remain multicellular 1

2. Binary Fission…in prokaryotes2

3. Binary Fission..DNA duplicates3

4. DNA separates & new cell wall divides cell in two4

5. 2 ‘new’ cells…identical5

6. Eukaryotic cell cycle Cell is ‘born’ Duplicates DNA Grows to…size?
Prepares to divide
Divides=mitosis 6

7. 7

8. 8

9. Control of mitosis:CYCLIN
Cyclins are a family of proteins that control the progression of cells through the cell cycle. 9

10. Chromosomes duplicate…S Phase10

11. 11

12. 12

13. 13

14. 14

15. Kinetochore (centromere)
Spindle fibers attach to kinetochore 15

16. 16

17. 17

18. 18

20. Mitosis produces identical offspring (2N---2N)20

21. Importance???
Growth
Replacement 21

22. Cancer?
Unregulated mitosis
Benign
Malignant/ metastasis 22

23. Unlike normal cells, which respond to density-dependent inhibition, tumor cells continue to divide, and multiply at an increased rate until all available nutrient supplies are depleted. When tumor cells are benign, they remain at the original site. When they are malignant, however, the tumor quickly becomes invasive: at this point, the mass is known as cancer.

24. Sometimes, cancerous tumors contain cells capable of triggering the formation of blood vessels specifically designed to create a nutrient supply for the mass. Malignant cells then gain a pathway via which they can travel to other parts of the body. When this occurs, the tumor has metastasised.

25. Name stage of mitosis 25

26. Name stage of mitosis 26

27. Name stage of mitosis 27

28. Name stage of mitosis 28

29. Name stage of mitosis 29

30. Name stage of mitosis 30

31. Name stage of mitosis 31

32. Name stage of mitosis 32