Link is: https://classes.uaa.alaska.edu/bbcswebdav/pid-6617027-dt-content-rid-29
ID: 53361 • Letter: L
Question
Link is: https://classes.uaa.alaska.edu/bbcswebdav/pid-6617027-dt-content-rid-29838327_1/courses/201503_78080/Week5%20Tumor%20suppressorsKch10.pdf
Which of the following statements is true?
Amplification of tumor suppressor genes occurs in many tumors.
Both copies of a tumor suppressor gene must acquire a mutation to promote carcinogenesis.
Constitutive activation of a tumor suppressor gene is a transforming event.
Changes that prevent its phosphorylation are a common Rb mutation in cancer.
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Which of the following statements about cell fusion is true?
Sendai virus causes nuclei from two different cells to fuse.
Fusions between cancer cells and normal cells result in uncontrolled growth of the hybrid due to oncogenes expressed in the cancer cell.
Hybrids resulting from fusions of cancer cells and normal cells maintain the combined chromosome sets indefinitely.
Fusions between cancer cells and normal cells typically create hybrids that initially behave like normal cells.
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Which of the following would NOT be likely to result in cancer-promoting loss of heterozygosity (LOH) at a given tumor suppressor locus?
Gene conversion in which a mutated tumor suppressor allele is used as the source of information to alter the second allele.
Meiotic nondisjunction in which one cell receives a single chromosome, which contains a mutated tumor suppressor.
A second mutation at the functional allele resulting from increased mutability in the developing cancer cell.
Deletion of a large region of a chromosome containing the normal allele.
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Which of the following is true of Rb?
Familial retinoblastoma results from the inheritance of a single germline mutation of one allele of Rb.
Patients with retinoblastoma exhibit Rb LOH in all tissues of the body.
Rb prevents E2F from activating transcription by phosphorylating E2F.
Rb is activated by the Ras-MAPK pathway.
Amplification of tumor suppressor genes occurs in many tumors.
Both copies of a tumor suppressor gene must acquire a mutation to promote carcinogenesis.
Constitutive activation of a tumor suppressor gene is a transforming event.
Changes that prevent its phosphorylation are a common Rb mutation in cancer.
Explanation / Answer
1. The right answer is B.
Both copies of a tumor suppressor gene must acquire a mutation to promote carcinogenesis.
As per the two hit hypothesis, both alleles, that code for a particular protein of tumor suppressor genes must be affected to promote carciongensis. In case only one allele for the gene is damaged, other gene perfectly code for the correct protein.
2. The answer is A.
Sendai virus causes nuclei from two different cells to fuse.
Biologists use three methods more prominently for cell fusion.
Electrical cell fusion, Polyehtylene glycol (PEG) cell fusion and Sendai virus induced cell fusion.
Sendai virus induced cell fusion occurs at different stages of temprature. In first stage which lasts for 10 minutes, absorption and inhibition of virus by viral antibodies takes place. The second stage is pH dependent and lasts for 20 minutes. The third stage named as antibody-refractory stage, viral envelope constituents remain detectable on the surface of cells. The last stage involves the completion of cell fusion and formation of syncitium. During this stage, cell fusion becomes evident and HA neuraminidase and fusion factors dissappeared.
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