Many Tumor Cells Are Able Divide Uncontrollably in Cell Culture

question 49

Multiple Choice

Many tumor cells are able divide uncontrollably in cell culture in the laboratory. Some of these cell lines have genomes with a mutant tumor-suppressor gene. Adding a wild-type copy of this tumor-suppressor gene to the genomes of these cells reduces their ability to divide in culture. In contrast, adding a wild-type copy of a proto-oncogene to the genomes of a tumor cell line with an activated oncogene doesn't have any effect on the uncontrolled cell division shown by this line. Which of the following statements BEST explains why adding a wild-type proto-oncogene doesn't affect cell division in these cell lines?

• A) Most point mutations that produce activated oncogenes are dominant gain-of-function mutations.
• B) Many proto-oncogenes encode proteins that act to promote apoptosis.
• C) Many proto-oncogenes encode proteins involved in DNA repair.
• D) Many proto-oncogenes are inherited as recessive mutations.
• E) Most protein products of proto-oncogenes don't have a role in cell division.

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Definitions:

Reliable

Capable of being trusted or depended on; consistently good in quality or performance.

Metaphor

A descriptive type of analogy, frequently found in literature.

Necessarily Follows

A logical condition where the conclusion is an inevitable result of the premises; if the premises are true, then the conclusion cannot be false.

Inductive

A method of reasoning in which the premises are viewed as supplying strong evidence for the truth of the conclusion.