Question 1

Which of the following best describes a frameshift mutation, and what is its most likely effect on the resulting protein?

Accepted Answer

An insertion or deletion of bases not in multiples of three; likely causes a shift in the reading frame and a nonfunctional protein.

Question 2

A mutation changes the codon GAA (glutamic acid) to GAG (also glutamic acid). What type of mutation is this, and why?

Accepted Answer

Silent mutation; the amino acid remains the same due to the degeneracy of the genetic code.

Question 3

Which of the following is a consequence of phosphorylation of eIF2α during cellular stress?

Accepted Answer

Blockage of translation initiation, reducing overall protein synthesis.

Question 4

A patient with Marfan syndrome has one mutated and one normal FBN1 allele. This is an example of:

Accepted Answer

Haploinsufficiency, where one functional allele does not produce enough protein for normal function.

Question 5

Which of the following best explains why RNA viruses, such as HIV, evolve more rapidly than DNA viruses?

Accepted Answer

RNA polymerases lack proofreading activity, resulting in higher mutation rates.

Question 6

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 7

Which of the following DNA repair mechanisms is responsible for correcting mismatches that escape proofreading during DNA replication?

Accepted Answer

Mismatch repair

Question 8

A mutation changes a leucine codon (CUA) to a proline codon (CCA). Which of the following best describes this mutation?

Accepted Answer

Non-conservative missense mutation

Question 9

Which of the following statements about the wobble hypothesis is correct?

Accepted Answer

It allows a single tRNA to recognize multiple codons due to flexible base pairing at the third codon position.

Question 10

Which of the following mutagens is most likely to cause frameshift mutations by inserting between DNA bases?

Accepted Answer

Intercalating agents such as acridine orange

Question 11

A mutation changes a purine to another purine. What is this type of mutation called?

Accepted Answer

Transition

Question 12

Which of the following best describes a dominant-negative mutation?

Accepted Answer

A mutant protein that interferes with the function of the wild-type protein.

Question 13

Which of the following is a likely consequence of a thymine dimer caused by UV radiation if not repaired?

Accepted Answer

Distortion of the DNA helix, leading to replication errors and possible mutations

Question 14

Which of the following best explains why silent mutations can still affect gene expression?

Accepted Answer

They can alter codon usage bias, affecting translation efficiency or mRNA stability.

Question 15

A patient inherits a mutation in a tumor suppressor gene that results in no functional protein being produced. What type of mutation is this?

Accepted Answer

Null mutation (complete loss-of-function)

Question 16

Which of the following best describes the effect of a base analog such as 5-bromouracil on DNA?

Accepted Answer

It mimics normal bases and can cause mispairing during replication, leading to mutations.

Question 17

Which of the following is true regarding the relationship between genome size and mutation rate in cellular organisms?

Accepted Answer

Larger genomes have lower per-base mutation rates but accumulate more total mutations per generation.

Question 18

Which of the following is a real-life example of a disease caused by a dominant-negative mutation?

Accepted Answer

Osteogenesis imperfecta (collagen disorders)

Question 19

A cytosine in DNA is deaminated to uracil. If not repaired, what is the most likely outcome after one round of DNA replication?

Accepted Answer

A transition mutation (C-G to T-A)

Question 20

Which of the following best describes the role of ubiquitination in the regulation of the noncanonical NF-κB pathway?

Accepted Answer

It targets NIK for degradation, turning the pathway off.

Mutations and DNA Repair: Mechanisms, Types, and Biological Impact

Study Guide - Practice Questions