Multiple Choice
Which DNA repair mechanism is primarily responsible for correcting thymine dimers caused by ultraviolet (UV) light exposure?
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17. Mutation, Repair, and Recombination
DNA Repair
Multiple Choice
In DNA repair pathways, DNA repair enzymes most directly use which of the following as their substrate?
A
Ribosomal RNA (rRNA) needing nucleotide replacement
B
Damaged DNA containing lesions such as mismatches, abasic sites, or modified bases
C
Newly synthesized proteins requiring removal of misfolded amino acids
D
Free deoxyribonucleoside triphosphates (dNTPs) in the cytosol
Verified step by step guidance1
Understand the role of DNA repair enzymes: These enzymes are specialized proteins that identify and correct damage in DNA molecules to maintain genetic integrity.
Identify the substrate of DNA repair enzymes: The substrate is the molecule upon which an enzyme acts. For DNA repair enzymes, this substrate must be related to DNA that has incurred damage or errors.
Consider the options given: Ribosomal RNA (rRNA) is involved in protein synthesis, not DNA repair; newly synthesized proteins with misfolded amino acids are handled by protein quality control systems, not DNA repair enzymes; free deoxyribonucleoside triphosphates (dNTPs) are building blocks for DNA synthesis, not the direct substrate for repair enzymes.
Focus on damaged DNA: DNA repair enzymes recognize and bind to damaged DNA regions containing lesions such as mismatches, abasic sites (missing bases), or chemically modified bases, which are the direct substrates for repair.
Conclude that the correct substrate for DNA repair enzymes is damaged DNA containing lesions, as these enzymes act to identify and correct these specific abnormalities to restore DNA integrity.
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