Difficulty: Easy
Correct Answer: General (homologous) recombination
Explanation:
Introduction / Context:
Cells exchange DNA via distinct recombination mechanisms. Homologous recombination underlies faithful DNA repair, meiotic crossing-over, and integration of very similar sequences. Recognizing the correct category is essential in genetics and biotechnology.
Given Data / Assumptions:
Concept / Approach:
General (homologous) recombination aligns matching sequences and swaps strands through a Holliday junction intermediate, ensuring precise crossover. Site-specific recombination uses dedicated recombinases at short recognition sites (for example, att); replicative recombination can describe transposition mechanisms; mutagenic/illegitimate recombination does not require long homology and is error-prone.
Step-by-Step Solution:
Identify hallmark: long stretches of homology dictate the mechanism.Associate with RecA/Rad51 and Holliday structures.Select “general (homologous) recombination.”
Verification / Alternative check:
Experimental genetic mapping in bacteria and meiosis in eukaryotes both demonstrate homologous recombination frequency depends on sequence identity and distance between markers.
Why Other Options Are Wrong:
Common Pitfalls:
Equating any recombination with homologous; mechanisms are specialized and context-dependent.
Final Answer:
General (homologous) recombination
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