Question 1

Which type of point mutation results in a premature stop codon, leading to a truncated polypeptide?

Accepted Answer

Nonsense mutation

Question 2

A patient is exposed to nitrous acid, which deaminates cytosine to uracil. What is the most likely consequence during DNA replication?

Accepted Answer

Uracil will pair with adenine, leading to a transition mutation.

Question 3

Which of the following best describes a frameshift mutation?

Accepted Answer

An addition or deletion of nucleotides not in multiples of three, altering the downstream amino acid sequence

Question 4

A mutation occurs in the promoter region of a gene. What is a likely effect?

Accepted Answer

It may increase or decrease the rate of transcription.

Question 5

Which of the following is a characteristic of germ-line mutations but not somatic mutations?

Accepted Answer

They are inherited by offspring.

Question 6

Which chemical mutagen acts by inserting between DNA bases and distorting the double helix?

Accepted Answer

Benzo(a)pyrene

Question 7

What is the primary effect of UV light on DNA?

Accepted Answer

It causes thymine dimers, which can lead to incorrect base incorporation.

Question 8

Which DNA repair mechanism removes a region of damaged DNA and uses the undamaged strand as a template for resynthesis?

Accepted Answer

Nucleotide excision repair

Question 9

A patient with xeroderma pigmentosum is highly sensitive to sunlight. This is due to a defect in which DNA repair pathway?

Accepted Answer

Nucleotide excision repair

Question 10

Which of the following statements about cancer is correct?

Accepted Answer

Most cancers originate from a single cell that accumulates multiple mutations.

Question 11

Which genetic change is most likely to convert a proto-oncogene into an oncogene?

Accepted Answer

A missense mutation that increases protein activity

Question 12

The Ras protein is involved in cell signaling. An oncogenic mutation in Ras most likely results in:

Accepted Answer

Constant activation of the signaling pathway, promoting uncontrolled cell division

Question 13

Which of the following is NOT a common mechanism by which tumor-suppressor gene function is lost?

Accepted Answer

Gene amplification

Question 14

The 'two-hit' model for retinoblastoma explains that:

Accepted Answer

Both alleles of the Rb gene must be mutated for cancer to develop.

Question 15

A chromosomal translocation that fuses two genes can result in:

Accepted Answer

A chimeric gene that may act as an oncogene

Question 16

Which of the following best describes the function of p53 in the cell cycle?

Accepted Answer

It halts the cell cycle in response to DNA damage and can induce apoptosis.

Question 17

A virus integrates its genome near a proto-oncogene, causing overexpression of the gene. This is an example of:

Accepted Answer

Retroviral insertion

Question 18

Which of the following is a likely consequence of a mutation in a splice site?

Accepted Answer

Improper removal of introns, leading to abnormal mRNA

Question 19

Which of the following best explains why most cancers are not inherited?

Accepted Answer

Most cancer-causing mutations occur in somatic cells and are not passed to offspring.

Question 20

A patient is diagnosed with chronic myelogenous leukemia (CML) due to a translocation between chromosomes 9 and 22. What is the molecular consequence of this translocation?

Accepted Answer

Formation of a chimeric bcr-abl gene that acts as an oncogene

Chapter 15

Study Guide - Practice Questions

Study Guide - Flashcards