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13 Cards in this Set
- Front
- Back
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Define carcinogenesis. |
Production of cancer. The process by which normal cells are transformed into cancer cells |
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Define cancer. |
A class of diseases characterized by abnormal and uncontrolled growth of cells with the potential to invade or travel to other parts of the body |
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What are carcinogens? |
Any substance that is an agent directly involved in causing cancer |
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What are the two types of carcinogens? |
1) Genotoxic - interact with DNA and alter genes
2) Epigenetic - do not interact directly with DNA but enhance tumour caused by genotoxic carcinogens |
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What are the two types of genotoxic carcinogens? |
1) Primary carcinogens 2) Procarcinogens |
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What is a primary carcinogen? |
Also known as direct or ultimate genotoxicants. A genotoxic carcinogen which affects DNA without any activation in the body. (The chemical itself is very active) |
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Give some examples of primary carcinogens. |
Ethylene dibromide Nitrosamides Nitrosoureas |
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What is a procarcinogen? |
Genotoxic carcinogens which require bio-activation in order to interact with the DNA. Chemical cannot cause cancer itself. This group includes most carcinogens. |
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Give some examples of pro-carcinogens. |
PAH Nitrosamines Alfatoxin B Vinyl chloride |
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What are the 4 major DNA lesions caused by chemicals? |
Alkylation - covalent adduct formed between the chemical and a DNA base Intercalation - non-covalent stacking of the chemical between adjacent base pairs Cross-linkage - formations of 2 covalent bonds within or between DNA strands Breakage - scission of the DNA helix |
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What are the 4 types of epigenetic carcinogens? |
1) Co-carcinogens 2) Promoters 3) Solid state carcinogens 4) Immuno-supressive drugs |
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Give some examples of pro-carcinogens. |
Polycyclic aromatic hydrocarbons. >Benzo-a-pyrene (most reactive) >N2-fluorenylactamide >4-dimethylaminoazobenzene >Senecio alkaloids >Aflatoxin B >Safrole >3-hydroxyxanthine >Dimethylnitrosamine
All generate electrophillic compounds which attack lone paired electrons in DNA |
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Give some examples of direct carcinogens. |
Electrophilic compounds >Alkyl imines >Alkylene Epoxides >Aryl epoxides >Lactones >Sulfate Esters >Mustards >Active halogen compounds
Many of these compounds contain small rings such as epoxides which have steric strain. |
