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15 Cards in this Set
- Front
- Back
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What are G1/G2 phases?
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Gap phases - nothing obvious occuring
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What is S phase?
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Synthesis of DNA
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What is M phase?
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Mitosis
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What order do the phases come in?
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G1 -> S -> G2 -> M
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What normally stops cell division? [4]
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1) Lack of positive signals 2) Contact inhibition 3) 'All Clear' - i.e. clear of DNA damage 4) Cell senescence [pre-determined limit]
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How do cancer cells continue to multiply in the absence of external signals?
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1) Don't respond to contact inhibition 2) Continue to divide despite abnormal DNA [don't wait for All-clear] 3) ignore cell senescence -> have more active telomerases
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What are proto-oncogenes?
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Genes responsible for providing the positive signals that lead to cell division [or cell death]
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What are oncogenes?
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Defective proto-oncogenes that allow the cell to divide in an unregulated manner
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What are tumor supressors?
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genes involved in transcription, DNA repair, etc. Their loss may allow abnormal cell behavior -> cancer
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What are induced mutations?
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Mutations caused by radiation, chemicals, oxygen radicals, genetics, or viruses
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Describe the action of radiation on DNA
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1) UV causes DNA point mutations 2) X-rays break the DNA double helix, leading to translocation and other chromosomal damage
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List common chemical carcinogens
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1) benzo-a-pyrene [cigarettes] 2) aflatoxin 3) benzene, vinyl chloride, tobacco
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Describe the action of viruses on DNA
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1) insert their own genes into DNA 2) may carry [corrupted] copies of DNA from former host-cells 3) both DNA and RNA viruses associated w/ cancer
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What is a carcinoma?
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Derived from epithelial cells [skin, organs, GIT, airway]
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What is a sarcoma?
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Derived from muscle, bone, cartilige, fat, connective tissue
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