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Cell Cycle
and
Cancer
Control of the Cell Cycle and Cancer
I) Check points1. 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 Cancer1. Proto-oncogenes – regulate cell growth, division,
and their ability to adhere to other cells
2. Oncogenes – caused by a mutation n the protooncogene, 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 cancer
2. Sarcoma – cancer of the bone or muscles
3. Lymphoma – tumors in the lymphatic system
4. Leukemia – uncontrolled growth of white
blood cells