CH 23 Cancer Genetics – Flashcards
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tumor cells acquire more mutations that allow them to become increasingly more aggressive in proliferating and eventually outgrow their predecessors and take over the clone
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colonial evolution
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dominant-actin stimulatory genes that cause cancer
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oncogenes
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inhibitory genes in cancer
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tumor-suppressor genes
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normal cellular genes responsible for basic cellular functions, when mutated contribute to the development of cancer
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proto-oncogenes
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enzymes that add phosphate groups to other proteins, only functional when associated with cyclin protein
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cyclin-dependent kinases
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external signals (hormones & growth factors) trigger a cascade of intracellular reactions that stimulate/inhibit cell cycle
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signal transduction pathway
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formation of new blood vessels
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angiogenesis
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What is the difference between an oncogene and a tumor-suppressor gene?
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An oncogene stimulates cell division, whereas a tumor-suppressor gene inhibits cell growth.
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Why do mutations in genes that encode DNA-repair enzymes often produce a predisposition to cancer?
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Mutations that affect DNA repair result in high rates of mutation. Mutations may convert proto-oncogenes into oncogenes or inactivate tumor-suppressor genes.
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How do chromosome deletions, inversions, & translocations may cause cancer?
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All involve breakage & rejoining of chromosomal DNA, rejoining brings together segments of DNA that were previously distant from eachother. May inactivate tumor suppressor genes, put a strong promoter next to a proto-oncogene causing overexpression of the proto-oncogene, or may bring two parts of genes together creating a new oncogene.
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How do viruses contribute to cancer?
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Retroviruses have strong promoters - may cause over expression of a proto-oncogene in the host genome. May inactivate tumor suppressor gene. Some retroviruses carry their own oncogenes, others express gene products that deactivate tumor suppressor proteins.
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If cancer is fundamentally a genetic disease, how might an environmental factor such as smoking cause cancer?
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Environmental factors cause cancer by acting as mutagens. Higher rates of mutation cause higher rates of inactivation of tumor suppressor genes or conversion of proto-oncogenes to oncogenes.
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