po
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In an experiment, biologic characteristics of neoplastic and non-neoplastic cells are analyzed in culture. It is observed that cell division in cells derived from malignant neoplasms, but not in normal cells, is aided by the presence of an enzyme which repairs progressive chromosomal shortening. The lack of chromosomal shortening allows the malignant cells to undergo many more divisions than the normal cells. Which of the following enzymes is most likely to have this effect?
A Reverse transcriptase
B DNA polymerase
C Telomerase
D Protein kinase
E Topoisomerase
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| SmokyWaters
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C
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| SILVER
DoWhatYouGotToDo!
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C Telomerase ??
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Expecting the world to treat you fairly because you are a good person, is like expecting the lion not to attack you because you are a vegetarian.
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| drhouse
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C for sure
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everybody can do it.... its just matter of time
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| po
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(C) CORRECT. The telomerase synthesizes telomeric chromosomal ends. The so-called 'immortal' neoplastic cell lines may result from the presence of this enzyme. Interfering with it may promise a new cancer therapy.
(A) Incorrect. This is the enzyme used by retroviruses, such as human immunodeficiency virus, to transcribe their RNA into proviral DNA that is incorporated into the host cell.
(B) Incorrect. DNA polymerase generates copies of DNA strands, and it is found in normal cells.
(D) Incorrect. Protein kinases are often the 'second messengers' in cells that control cell growth, and their function may be altered by oncogenic activity.
(E) Incorrect. DNA topoisomerase is an enzyme that untangles DNA at the end of mitosis. Antineoplastic drugs that target topoisomerase interfere with this enzyme to produce DNA strand breakage and cell death.
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