Regulating the Cell Cycle

1. Regulating the Cell Cycle Biology 392 Chapter 10-3

2. Cancer • One in three people will develop cancer. • One in four people will die of cancer. • More than 1500 Americans died each day of cancer this year. • Over 1,000,000 cases of skin cancer will be diagnosed this year. • Cancer is the leading cause of death among Americans under the age of 85.

3. What is Cancer? • Disorder in which some of the body’s cells lose the ability to control growth • 100’s of different types • Do not respond to internal &/or external signals • Continuously divide – forming masses of cells called tumors. • Cancer cells can break from a tumor and spread throughout the body (metastasize)

4. Can you die from skin cancer?

5. What’s happening in the petri dish? Section 10-3 How does this represent the healing process? This is normal  the cells eventually stop

6. What causes the cell cycle to continue? Is it automatic? Does it ever stop?

7. Cell Cycle Rates Cells do not move through the cell cycle at the same rate Cells in a developing embryo replicate rapidly- 3 minutes Average time of cell cycle- 20 hours Lining of esophagus- 2-3 days Lining of small intestine- 1-2 days Lining of large intestine- 6 days Red blood cells-120 days White blood cells- 10hrs-decades

8. Hypothesis: Substance X will cause a cell to start mitosisSubstance X = CYCLIN Section 10-3 The sample is injected into a second cell in G2 of interphase. A sample of cytoplasm is removed from a cell in mitosis. As a result, the second cell enters mitosis. Cyclin cellular protein that regulates the timing of the cell cycle in eukaryotic cells;  help create spindle

9. Cell Cycle Regulators • INTERNAL • Proteins that respond to signals inside the cell • Checkpoints during interphase: Make sure all DNA has been properly made Make sure all chromosomes have attached to a spindle • EXTERNAL • Proteins that respond to events outside the cell • Speed up or slow down cell cycle • Respond to environment and “crowding”

10. Cell Cycle Regulators

11. Causes of Cancer Environment  sun, chemicals Not exercising  obesity is linked to several Genetics (but not necessarily inherited) Mutations in genes that regulate cell cycle Example: p53  gene responsible for halting the cell cycle until all chromosomes have replicated properly  Defects in this gene is a precursor to cancer

12. Progression of Cancer

13. Kinds of Cancers • SOLID TUMORS • Carcinomas  originate from surface cells (skin, wall of intestine, surface of organs) • Sarcomas  bone, cartilage, fat, muscle • “LIQUID” TUMORS • Leukemias  circulate in blood stream, from blood • Lymphomas  developed in lymph system

14. 2006 Estimated US Cancer Deaths* Men291,270 Lung & bronchus 31% Colon & rectum 10% Prostate 9% Pancreas 6% Leukemia 4% Liver & intrahepatic 4%bile duct Esophagus 4% Non-Hodgkin 3% lymphoma Urinary bladder 3% Kidney 3% All other sites 23% Women273,560 26% Lung & bronchus 15% Breast 10% Colon & rectum 6% Pancreas 6% Ovary 4% Leukemia 3% Non-Hodgkin lymphoma 3% Uterine corpus 2% Multiple myeloma 2% Brain/ONS 23% All other sites ONS=Other nervous system. Source: American Cancer Society, 2006.

15. Treatments • Surgery – remove the affected cells • Radiation – high-dose X-rays kill cells • Chemotherapy – drugs kill cells • Hormone therapy – hormones stop cell growth

16. Video links • http://video.about.com/cancer/Chemotherapy.htm • http://video.about.com/cancer/Chronic-Myeloid-Leukemia.htm • http://video.about.com/cancer/CyberKnife-Radiosurgery.htm • http://video.on.nytimes.com/index.jsp?fr_story=cde8a179a490d9a9fe977c6df92fb8fe3b88a538 • (lung cancer and CT scans)