Multiple Choice
Which enzyme joins the gaps between synthesized DNA fragments of the lagging strand?
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14. DNA Synthesis
DNA Repair
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Double-strand breaks in DNA are typically repaired by which of the following mechanisms?
A
Base excision repair
B
Mismatch repair
C
Nucleotide excision repair
D
Homologous recombination
Verified step by step guidance1
Understand the nature of double-strand breaks in DNA: These are severe types of DNA damage where both strands of the DNA helix are broken. Such breaks can compromise genetic integrity and lead to cell death if not repaired properly.
Review the repair mechanisms listed: Base excision repair, mismatch repair, and nucleotide excision repair are mechanisms that typically address single-strand damage or specific types of errors, such as mismatched bases or small lesions. They are not equipped to handle double-strand breaks.
Introduce homologous recombination: Homologous recombination is a repair mechanism specifically designed to fix double-strand breaks. It uses a homologous sequence (usually from a sister chromatid) as a template to accurately repair the break, ensuring genetic fidelity.
Explain why homologous recombination is the correct answer: This mechanism is highly precise because it relies on the homologous sequence to guide the repair process, making it ideal for repairing double-strand breaks without introducing mutations.
Summarize the key concept: Double-strand breaks are repaired by homologous recombination because it ensures accurate restoration of the DNA sequence, unlike the other mechanisms listed, which are suited for different types of DNA damage.
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