Question 1

Which of the following best describes the difference between a proto-oncogene and an oncogene?

Accepted Answer

A proto-oncogene is a gene whose normal product promotes cell growth and proliferation, while an oncogene is a mutated or misexpressed version that causes increased activity and promotes oncogenesis.

Question 2

Which type of genetic mutation is most likely to convert a proto-oncogene into an oncogene?

Accepted Answer

Hypermorph (increase in normal function)

Question 3

A patient with xeroderma pigmentosum has a mutation in which DNA repair pathway, leading to extreme sensitivity to UV light?

Accepted Answer

Nucleotide excision repair (NER)

Question 4

Which of the following statements about tumor suppressor genes is correct?

Accepted Answer

Tumor suppressor genes regulate cell-cycle checkpoints and apoptosis; both alleles usually need to be mutated for cancer to develop.

Question 5

The p53 gene is frequently mutated in cancer. What is its primary function in normal cells?

Accepted Answer

It regulates the transcription of genes involved in cell cycle checkpoints, apoptosis, and DNA repair.

Question 6

Which of the following best explains why only one mutated allele of a proto-oncogene is sufficient to promote cancer?

Accepted Answer

Oncogenes confer a dominant gain-of-function phenotype, so a single mutated allele can drive uncontrolled growth.

Question 7

A patient inherits a mutation in one allele of a tumor suppressor gene. What is the most likely consequence?

Accepted Answer

The patient has an increased risk of cancer, but both alleles usually need to be inactivated for cancer to develop.

Question 8

Which of the following physical mutations is most likely to result in a gain-of-function oncogene?

Accepted Answer

Heterozygous missense mutation

Question 9

Which of the following best describes the role of apoptosis in cancer prevention?

Accepted Answer

Apoptosis is a form of programmed cell death that eliminates cells with severe chromosome damage, preventing cancer.

Question 10

A cancer cell is found to have a loss-of-function mutation in both alleles of a DNA repair gene. What is the most likely consequence?

Accepted Answer

Decreased DNA repair and increased mutation rate, leading to genomic instability

Question 11

Which of the following is a key difference between somatic and germline mutations in cancer?

Accepted Answer

Germline mutations can be passed to offspring, while somatic mutations cannot.

Question 12

Which of the following best explains why cancers are considered multigenic diseases?

Accepted Answer

They require multiple mutations in different genes, such as proto-oncogenes and tumor suppressors, to develop.

Question 13

A patient with a family history of colon cancer undergoes genetic testing and is found to have a mutation in the APC gene. What is the significance of this finding?

Accepted Answer

APC is a tumor suppressor gene, and mutation increases the risk of developing colon cancer due to loss of cell cycle regulation.

Question 14

Which of the following best describes the process of hyperplasia?

Accepted Answer

An increase in cell proliferation without a change in cell identity

Question 15

Which checkpoint in the cell cycle is responsible for monitoring DNA integrity before DNA synthesis?

Accepted Answer

G1/S checkpoint

Question 16

A patient is found to have a heterozygous missense mutation in the ras gene. What is the most likely effect of this mutation?

Accepted Answer

Gain of ras function, leading to increased cell proliferation and potential oncogenesis

Question 17

Which of the following is NOT a typical property of cancer cells?

Accepted Answer

Enhanced DNA repair and reduced mutation rate

Question 18

Which of the following best explains why individuals with xeroderma pigmentosum have a much higher risk of developing skin cancer?

Accepted Answer

They have defective nucleotide excision repair, leading to accumulation of UV-induced DNA damage.

Question 19

Which of the following scenarios best illustrates the concept of mosaicism in cancer genetics?

Accepted Answer

A person develops a mutation in a subset of somatic cells, leading to a patch of tissue with different genetic makeup.

Question 20

Which of the following best describes why cancer is not considered a single disease?

Accepted Answer

Cancers are a collection of diseases characterized by inappropriate growth and multiple mechanisms of cell malfunction.

Cancer Genetics: Mechanisms, Mutations, and Inheritance - Nov 14

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