$$\text{C-G} \rightarrow \text{T-A}$$

Question 1

Which of the following best describes a missense mutation at the molecular level?

Accepted Answer

A base substitution that changes one amino acid to another.

Question 2

A patient is diagnosed with β-thalassemia. Which type of mutation is most likely responsible for this disease?

Accepted Answer

A point mutation in the coding region of the β-globin gene.

Question 3

Which repair mechanism is most likely to fix a mismatch that occurs during DNA replication?

Accepted Answer

Mismatch repair

Question 4

Depurination leads to the loss of a purine base from DNA. What is the most common outcome when the cell fills in the missing nucleotide?

Accepted Answer

The cell usually inserts an adenine.

Question 5

Which of the following equations represents the transition mutation caused by deamination of unmethylated cytosine?

Accepted Answer

$$	ext{C-G} ightarrow 	ext{T-A}$$

Question 6

A frameshift mutation is most likely to occur due to which of the following?

Accepted Answer

Insertion or deletion of one or more base pairs

Question 7

Which of the following best explains why Huntington’s disease is classified as a trinucleotide repeat disorder?

Accepted Answer

It is caused by strand slippage during DNA replication, leading to expansion of CAG repeats.

Question 8

Which repair mechanism is most appropriate for a double-stranded DNA break when a homologous chromosome is available?

Accepted Answer

Homologous recombination

Question 9

A mutation in the promoter region of a gene can lead to which of the following outcomes?

Accepted Answer

Altered transcription levels of the gene

Question 10

Which of the following is a characteristic of somatic mutations?

Accepted Answer

They are only present in non-reproductive tissues and are not inherited.

Question 11

Which of the following diseases is caused by a mutation in mitochondrial DNA?

Accepted Answer

MELAS syndrome

Question 12

A base-pair substitution creates a cryptic splice site in the β-globin gene. What is the most likely molecular consequence?

Accepted Answer

The mature mRNA will lose nucleotides, potentially altering the protein.

Question 13

Which of the following best describes the difference between single gene and multifactorial diseases?

Accepted Answer

Single gene diseases are caused by mutations in one gene, while multifactorial diseases involve multiple genes and environmental factors.

Question 14

Which of the following equations represents the effect of depurination on DNA sequence?

Accepted Answer

$$	ext{G-C} ightarrow 	ext{A-T}$$

Question 15

Which of the following is a consequence of a nonsense mutation?

Accepted Answer

Introduction of a premature stop codon.

Question 16

A patient with Klinefelter syndrome has which chromosomal composition?

Accepted Answer

XXY

Question 17

Which of the following best explains why lack of diversity in genetic data can be problematic for medical genomics?

Accepted Answer

It limits the ability to identify disease-causing variants in underrepresented groups.

Question 18

Which repair mechanism removes a stretch of approximately 25 nucleotides and replaces them based on the complementary strand?

Accepted Answer

Nucleotide excision repair

Question 19

A mutation occurs in the 5’ untranslated region (UTR) of a gene. Which of the following is a likely consequence?

Accepted Answer

Altered mRNA stability and regulation

DNA Damage, Repair, and Mutation: Mechanisms and Consequences

Study Guide - Practice Questions