What is the name for the recombination process that occurs between long homologous DNA sequences and drives accurate exchange?

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:

  • Sequences involved are homologous (high sequence identity).
  • Proteins such as RecA/Rad51 catalyze strand invasion and exchange.
  • Outcome is accurate exchange with minimal sequence alteration.

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:

  • Site-specific: needs unique short sites, not long homology.
  • Replicative: often refers to transposon copy-in events.
  • Mutagenic/illegitimate: non-homologous, error-prone.

Common Pitfalls:Equating any recombination with homologous; mechanisms are specialized and context-dependent.

Final Answer:General (homologous) recombination

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