Cell Cycle and

Cancer

Control of the Cell Cycle and Cancer

I) Check points- 1. G1 – if the cell is fully grown, proteins will move the cell into S -Some cells stop at this point and go into G0

2. G2 – DNA repair enzymes check if the cell is ready for mitosis

3. Mitosis – proteins signal the cell to exit mitosis

II) Cyclins- category of proteins which regulate the cell cycle, discovered in the 1980’s

-regulate the checkpoints and the timing of each mitosis phase

III) Cancer- disease of the cell cycle, uncontrolled cell growth

1. Cancer cells do not respond to the cyclins that regulate cell growth, they form masses (tumors) that can damage surrounding tissue. 2. Cyclins are coded for by genes. If a mutation occurs in the genes, the cyclins won’t function properly, and the cell cycle will just continue nonstop.

IV) Cell Division and Cancer-

1. Proto-oncogenes – regulate cell growth, division, and their ability to adhere to other cells

2. Oncogenes – caused by a mutation n the proto-oncogene, causes uncontrolled cell growth

3. Benign- tumor that causes no threat

4. Malignant – uncontrolled cells invade other parts of the body (cancer)

5. Tumor suppressor gene – prevents uncontrolled cell growth

6. Cancer cells ignore normal signals to stop growing:

-Continue to divide when not attached-Continue to divide when crowded-Continue to divide(normal cells only divide about 40 times)

7. Metastasis – spread of cancer cells beyond their original site

8. Carcinogen – substance that triggers the growth of cancer cells

9. Mutagen – substance that causes mutations

10. Some viruses may cause cancer by-Activating oncogenes-Causing mutations in proto-oncogenes

or tumor suppressor genes-Human papilloma virus causes

cervical cancer

V) Kinds of Cancer:1. Carcinoma – skin and tissue Ex.: breast cancer, lung cancer, liver or pancreatic cancer2. Sarcoma – cancer of the bone or muscles

3. Lymphoma – tumors in the lymphatic system

4. Leukemia – uncontrolled growth of white blood cells