KEY CONCEPT Cell cycle regulation is necessary for healthy growth.

1. KEY CONCEPTCell cycle regulation is necessary for healthy growth.

2. When is mitosis a good thing? • When you have to add or replace cells • growth & development • repair • replacement

3. Internal and external factors regulate cell division. • External factors include physical and chemical signals. • Growth factors are proteins that stimulate cell division. • Most mammal cells form a single layer in a culture dish and stop dividing once they touch other cells.

4. Regulation of Cell Cycle Check points at each phase

5. Cells will not divide if… • there are not enough nutrients to support cell growth • DNA is damaged • DNA has not been replicated …cell will be repaired / destroyed.

6. Two of the most important internal factors are kinases and cyclins. • External factors trigger internal factors, which affect the cell cycle.

7. webbed fingers • Apoptosis is programmed cell death. • a normal feature of healthy organisms • caused by a cell’s production of self-destructive enzymes • occurs indevelopmentof infants

8. When is mitosis a BAD thing • When cells reproduce & they are not needed • these cells take over organs, but don’t do the right job • they just keep making copies • cancer • damages organs

9. normal cell cancer cell bloodstream Cell division is uncontrolled in cancer. • Cancer cells form disorganized clumps called tumors. • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors.

10. Cancer cells do not carry out necessary functions. • Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

11. Growth of a tumor

12. Healthy Cells grow in a single layer stop dividing when they receive messages from neighbouring cells Cancer Cells do not respond to messages from neighbouring cells…continue to divide start to grow in multiple layers that form a tumor

13. Why would cells just make copies? • If DNA gets damaged, cells stop listening to correct instructions • mutations • Causes of mutations: • UV radiation • chemical exposure • radiation exposure • heat • cigarette smoke • pollution • age • genetics

14. Tumors • Benign tumor • abnormal cells remain at original site as a lump • most do not cause serious problems &can be removed by surgery

15. Tumors • Malignant tumor • cells leave original site • carried by blood system to other tissues • start more tumors • damage functions of organs throughout body

16. Watch how a tumor grows... http://www.hhmi.org/biointeractive/media/angiogenesis-lg.mov

17. Carcinogens are substances known to promote cancer. • Standard cancer treatments typically kill both cancerous and healthy cells.

18. side effects Treatments for cancers • Treatments kill rapidly dividing cells • chemotherapy • poisonous drugs that kill rapidly dividing cells • radiation • high energy beam kills rapidly dividing cells