Mutation, DNA damage and repair, and Antimicrobial Resistance

Which of the following types of DNA damage involves chemical bonds forming between adjacent bases due to UV radiation?

• Single-strand breaks

• Double-strand breaks

• Pyrimidine dimers

• Point mutations

During DNA replication, DNA polymerase can correct base-pairing errors through which of the following mechanisms?

• Base excision repair

• Mismatch repair

• Proofreading

• Nucleotide excision repair

Mismatch repair distinguishes the newly synthesized DNA strand from the parental strand by recognizing:

• Presence of pyrimidine dimers

• Methyl groups on the parental strand

• Strand breaks on the new strand

• DNA polymerase binding sites

Which DNA repair mechanism involves removing a damaged nucleotide base and replaces it without excising a large segment of DNA?

• Nucleotide excision repair

• Base excision repair

• Recombinational repair

• Photoreactivation

The SOS response in bacteria is best described as:

• A system to increase antibiotic resistance genes

• An emergency repair system that allows error-prone DNA repair

• A mechanism that removes methyl groups from DNA bases

• A repair pathway specific to UV-induced damage

Compare nucleotide excision repair and base excision repair. Which of the following statements correctly reflects a key difference?

• Base excision repair removes a patch of DNA, while nucleotide excision repair removes a single base.

• Nucleotide excision repair targets bulkier, helix-distorting lesions; base excision repair targets small base modifications.

• Both mechanisms are highly error-prone and introduce mutations.

• Neither mechanism uses DNA polymerase for gap filling.

What is the main difference between intrinsic and acquired antimicrobial resistance?

• Intrinsic resistance involves gene mutations, while acquired resistance is inherent to all members of a species.

• Intrinsic resistance is naturally present without prior antibiotic exposure; acquired resistance develops through mutations or gene transfer.

• Acquired resistance is reversible, intrinsic resistance is not.

• Intrinsic resistance only occurs in gram-positive bacteria.

Which of the following is NOT a factor contributing to the spread of antibiotic resistance?

• Use of antibiotics in animal feeds

• Incomplete antibiotic treatment courses by patients

• High outer membrane permeability in bacteria

• Lack of infection control in hospitals

A bacterial species that can turn off resistance genes when antibiotics are removed is displaying:

• Acquired resistance

• Intrinsic resistance

• Adaptive resistance

• Horizontal gene transfer

Why is recombinational repair considered a high-fidelity repair mechanism for double-strand breaks?

• It does not involve DNA polymerase.

• It uses a homologous DNA strand as a template for accurate repair.

• It introduces random mutations to accelerate evolution.

• It excises large DNA segments around the damage.