Question 1

Which of the following best describes the role of the RAS protein in cell signaling?

Accepted Answer

RAS protein acts as a molecular switch, cycling between an active GTP-bound state and an inactive GDP-bound state to regulate signal transduction.

Question 2

A chromosomal translocation between chromosomes 9 and 22 results in the formation of which oncogene, commonly associated with chronic myelogenous leukemia (CML)?

Accepted Answer

BCR-ABL

Question 3

What is the biochemical consequence of a RAS mutation that locks the protein in its GTP-bound form?

Accepted Answer

The RAS protein cannot hydrolyze GTP to GDP, resulting in continuous stimulation of cell growth and division.

Question 4

Which of the following is a direct result of defects in DNA repair genes such as BRCA1, BRCA2, or ATM?

Accepted Answer

Genomic instability, leading to mutations, chromosome breaks, and aneuploidy.

Question 5

The Philadelphia chromosome is an example of a chromosomal rearrangement that leads to cancer. Which mechanism best explains its oncogenic effect?

Accepted Answer

It results in the fusion of two genes, creating a constitutively active tyrosine kinase.

Question 6

Which of the following statements about retroviruses and oncogenes is correct?

Accepted Answer

Retroviruses can insert oncogenes into the DNA of a host cell, transforming it into a tumor-producing cell.

Question 7

A patient is diagnosed with acute promyelocytic leukemia (APL). Which chromosomal translocation is most likely responsible for this condition?

Accepted Answer

t(15;17)

Question 8

Which gene fusion product interferes with the normal function of the retinoic acid receptor and is associated with APL?

Accepted Answer

PML-RARA

Question 9

Genomic instability in cancer cells is often characterized by which of the following?

Accepted Answer

Widespread mutations, chromosome breaks, and aneuploidy.

Question 10

Which of the following best explains why HER2/NEU is a target for breast cancer therapy?

Accepted Answer

HER2/NEU encodes a growth factor receptor that is amplified and overexpressed in some breast cancers, promoting cell proliferation.

Question 11

Aneuploidy, commonly seen in cancer cells, is best defined as:

Accepted Answer

The presence of an abnormal number of chromosomes in a cell.

Question 12

Which of the following is a plausible outcome if a tumor cell escapes regulation by tumor suppressor or DNA repair proteins?

Accepted Answer

The cell may become immortal and continue dividing uncontrollably.

Question 13

Which of the following best describes the function of the PML-RARA fusion protein in APL?

Accepted Answer

It impairs the function of the PML protein and blocks differentiation of myeloid cells.

Question 14

A scientist observes that a normal cell becomes tumorigenic after the introduction of a specific gene from a tumor cell. This gene is most likely:

Accepted Answer

An oncogene.

Question 15

Which of the following is a common feature of genomic instability in cancer cells?

Accepted Answer

Frequent mutations and chromosomal rearrangements.

Question 16

Which of the following best explains why translocations involving oncogenes can lead to cancer?

Accepted Answer

They can place oncogenes under the control of highly active promoters, leading to uncontrolled cell growth.

Question 17

A patient with a mutation in the ATM gene is likely to experience which of the following?

Accepted Answer

Defective DNA repair, leading to increased genomic instability and cancer risk.

Question 18

Which of the following is a multi-step process that can lead to tumorigenesis?

Accepted Answer

Accumulation of mutations in oncogenes, tumor suppressor genes, and DNA repair genes.

Question 19

Which of the following best describes the effect of the BCR-ABL fusion protein in chronic myelogenous leukemia?

Accepted Answer

It acts as a constitutively active tyrosine kinase, promoting uncontrolled cell division.

Question 20

Which of the following is a likely consequence of widespread aneuploidy in tumor cells?

Accepted Answer

Disrupted gene dosage and altered cellular function.

Genetic Alterations, Oncogenes, and Cancer Cell Immortality

Study Guide - Practice Questions

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