1. Regulating The Cell Cycle

2. Not all cells divide!
Muscle cells and nerve cells do not divide once they are developed

3. Some cells divide frequently
Skin, digestive lining, blood cells

4. How does a cell know if it should divide?
Contact: when cells come into contact with one another they stop dividing
Density: when cells are too crowed, they stop dividing

5. Cyclins: -proteins that regulate cell cycle in eukaryotic cells
High cyclin = cell division
Low cyclin = no cell division

6. Cyclins: Messages from within the cell: internal regulators
Messages from outside cell: external regulators
Both control the production of cyclin

7. Cancer: Uncontrolled Growth
Cancer cells ignore normal cell signals and divide constantly
form masses = tumors
can damage surrounding tissues

8. Cancer: Uncontrolled Growth
Causes of cancer can be different:
smoking tobacco, radiation exposure, chemical exposure, viral infections

9. Cancer: Uncontrolled Growth
All cancers have 1 thing in common:
The control over the cell cycle has broken down!!