When Good Cells Go Bad

1. When Good Cells Go Bad Cell Cycle Control & Cancer

2. The Cell Cycle

3. The Cell Cycle • Not all cells in the body go through the cell cycle at the same rate • Muscle and nerve cells never go through mitosis after they mature. • Liver cells go through mitosis about once a year. • Skin cells go through mitosis every few hours.

4. Rate of Cell Division • Contact inhibition is turned off or on as needed. • Example, if a bone breaks the cells near the break will begin to divide until the break is filled.

5. Cyclins and Growth Factors • Proteins that regulate timing of cell cycle • Make sure cell cycle does not proceed until all previous steps have been completed. • Cyclins – cell cycle does not continue until previous steps are complete

6. Cell Cycle Control • G1 checkpoint – Has the correct signal to divide been given?

7. Cell Cycle Control • G2 checkpoint – Is the cell ready to divide?

8. Cell Cycle Control • M checkpoint – Are chromatids aligned at equator?

9. Cyclins and Growth Factors • Proteins that regulate timing of cell cycle • Make sure cell cycle does not proceed until all previous steps have been completed. • Cyclins – cell cycle does not continue until previous steps are complete • Respond to events in the body to speed or slow cell division. • Growth factors – stimulate mitosis for wound healing

10. Apoptosis • Programmed cell death (cell suicide” • When a cell is old, damaged, or no longer needed, it systematically dismantles itself.

11. Cancer • Cancer – a cell that divides inappropriately • Mutations in DNA that control cell cycle • Accumulations of multiple mutations transform normal cell to cancer cell • Each cancer cell has 6 – 8 mutations in genes that: • Control the cell cycle • Control cell death • Allow cell to obtain nutrients and move throughout the boyd

12. Cancer • Oncogenes – genes that encourage cell division (gas pedal) • Tumor-suppressor genes – genes that inhibit cell division (brakes) • In cancer cells, these genes are mutated. (Gas pedal gets stuck and brakes don’t work.)

13. How Cancer Grows Interactive Activity • http://www.teachersdomain.org/asset/tdc02_int_howcancergrw/ • Answer the following questions: • What are some ways cancer cells develop abnormally? • What are some ways that cancer cells differ from normal cells? • How does the body respond to cancer cells?