Cells tightly regulate the cell cycle through tumor suppressor genes that apply the brakes to cell division and growth promoting proteins that stimulate division. Cancer occurs when mutations inactivate tumor suppressor genes, removing the brakes and allowing cells to divide uncontrollably even when they are not supposed to. Many cancer cells have mutations in their tumor suppressor genes, disrupting the normal cell cycle controls and leading to uncontrolled cell proliferation.

1. Regulating the Cell Cycle Controlling Cell Division Page 250; 10-3

4. Apoptosis – programmed cell death

5. Cancer is a cell division disorder Cancer often works like this… Some DNA becomes mutated  this leads to the ‘command’ that stimulates cells to divide even though they are supposed to wait… [growth promoting proteins get ‘over-made’] Genes that inhibit cell division are called tumor suppressors. (these are good) Mutations can ‘inactivate’ these genes and the cell cycle “brake” is removed. Control proteins become inactivated. (this is bad) There is nothing to stop the cell from rapid and out of control division. MANY CANCER CELLS HAVE MUTATIONS IN THEIR TUMOR-SUPRESSOR GENES.

7. Page 252