GeneRegulation160-page15

GeneRegulation160-page15 - associated with mutations in...

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Gene Regulation - 15 From what we know today, the steps in cancer development include: Exposure to a carcinogen from the environment by ingestion, inhalation, etc., naturally or via contamination Entry of the carcinogen into a cell Initiation of cancer via sufficient DNA changes in cell division control genes Promotion and enhancement of cancer via cell transformation Tumor formation and uncontrolled cell growth No one knows why any one person gets cancer. Some cancers are familial, and probably genetic. Some cancers are related to the environment, especially the smoker's environment. A substance that causes a change in DNA that can lead to cancer is a carcinogen and exposure to a carcinogen is the first step in cancer. How does one get cancer? Most believe that the onset of cancer is an accumulation of mutations rather than one single alteration. This correlates with the increase in many cancers with aging. As briefly mentioned during our section on cell reproduction, many cancers are
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Unformatted text preview: associated with mutations in genes that regulate cell division. Such genes that normally control cell division but when mutated have the potential to induce cancer are called oncogenes. They are often called proto-oncogenes when functioning normally. Oncogenes also include genes that normally suppress tumor formation by monitoring DNA and cell division to ensure that all is well. The P53 tumor suppressor gene is one such gene mentioned earlier. P53 is a transcription factor for genes that keep a cell's DNA repaired and genes that delay the cell's rate of cell division so that there is time for DNA repair. If the cell is in bad shape, P53 activates cell suicide genes to prevent the harmful mutations from being passed on. Such cell death is called apoptosis, and is genetically programmed. When p53 is defective or missing, cancers are more likely because DNA damage isn't caught and repaired....
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