Question 1

Which of the following best describes the difference between proto-oncogenes and tumor suppressor genes?

Accepted Answer

Proto-oncogenes are genes that can cause cancer when mutated to become oncogenes, whereas tumor suppressor genes play a role in inhibiting cell division.

Question 2

A mutation in which type of gene would most likely result in uncontrolled cell growth, even in the absence of external signals?

Accepted Answer

A proto-oncogene that mutates to an oncogene.

Question 3

Which of the following statements about the Ras protein is FALSE?

Accepted Answer

Ras protein is a tumor suppressor that inhibits cell division.

Question 4

What is the consequence of a loss-of-function mutation in a tumor suppressor gene?

Accepted Answer

The cell may undergo uncontrolled division, increasing the risk of cancer.

Question 5

Which of the following best explains why oncogenes are dominant at the cellular level?

Accepted Answer

A single mutated allele can promote cell division even if the other allele is normal.

Question 6

Which of the following scenarios would most likely lead to the development of cancer?

Accepted Answer

A gain-of-function mutation in a proto-oncogene and a loss-of-function mutation in a tumor suppressor gene.

Question 7

Which of the following is a function of tumor suppressor genes?

Accepted Answer

Inhibiting cell division and promoting DNA repair.

Question 8

A patient is found to have a continuously active Ras protein due to a mutation. What is the most likely cellular outcome?

Accepted Answer

The cell will continuously divide, increasing the risk of tumor formation.

Question 9

Which of the following best describes the role of proto-oncogenes in normal cells?

Accepted Answer

They encode proteins that promote appropriate cell division in response to signals.

Question 10

If a cell acquires a mutation that inactivates both copies of a tumor suppressor gene, what is the most likely effect?

Accepted Answer

The cell will lose its ability to regulate cell division, increasing cancer risk.

Question 11

Which of the following is NOT a characteristic of oncogenes?

Accepted Answer

They require both alleles to be mutated to function.

Question 12

A researcher discovers a new gene that, when mutated, leads to the inability of cells to stop dividing. This gene is most likely a:

Accepted Answer

Tumor suppressor gene

Question 13

Which of the following best explains why tumor suppressor genes are considered recessive at the cellular level?

Accepted Answer

Both alleles must be inactivated for loss of function to occur.

Question 14

Which of the following is a direct result of a gain-of-function mutation in a proto-oncogene?

Accepted Answer

Uncontrolled cell proliferation

Question 15

A cell with a mutated Ras protein that cannot hydrolyze GTP will most likely:

Accepted Answer

Remain in a permanently active state, continuously signaling for cell division.

Signaling Defects, Oncogenes, and Tumor Suppressor Genes in Cancer

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