Gen Chap 19 – Flashcards
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Distinguish between oncogenes and proto-oncogenes.
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Oncogenes are genes that induce or maintain uncontrolled cellular proliferation associated with cancer. They are mutant forms of proto-oncogenes, which normally function to regulate cell division.
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In what ways can proto-oncogenes be converted to oncogenes?
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translocations point mutations gene amplification repositioning of regulatory sequences
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How do translocations such as the Philadelphia chromosome contribute to cancer?
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Genetic mapping established that certain genes were combined to form a hybrid oncogene ( BCR/ABL ) that encodes a 200kDa protein that has been implicated in the formation of chronic myelogenous leukemia.
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Genetic tests that detect mutations in the BRCA1 and BRCA2 oncogenes are widely available. These tests reveal a number of mutations in these genes - mutations that have been linked to familial breast cancer. Assume that a young woman in a suspected breast cancer family takes the BRCA1 and BRCA2 genetic tests and receives negative results. That is, she does not test positive for the mutant alleles of BRCA1 or BRCA2. Can she consider herself free of risk for breast cancer?
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No, she will still have the general population risk of about 10 percent.
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Which of the following statements describes metastasis?
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The ability to form secondary tumors at another site Cells from malignant tumors can break off from the main tumor, travel through the blood or lymph, and establish secondary tumors at another site.
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Cancer is best described as a ________.
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genetic disorder at the cellular level The location of genetic mutations and how they occur vary greatly. However, all cancers result from a genetic disorder at the cellular level
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What is the relationship between proto-oncogenes and oncogenes?
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Oncogenes are mutant forms of proto-oncogenes. Proto-oncogenes are normal cellular genes. Mutations can cause these to be permanently switched on, leading to uncontrolled cell division and cancer.
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What is the role of the p53 protein in the cell cycle in normal cells?
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It temporarily arrests the cell cycle in G1 before entering S. The p53 protein apparently arrests the cell cycle until any DNA damage has been repaired.
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Which of the following statements is TRUE regarding heritability of cancer?
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At least two mutational events are required for a cell to become cancerous. One copy of a mutated gene is not enough to trigger development of cancer. Mutation in the other copy of the gene is also required. In addition, mutations in other genes are often required to fully express the cancer.
