Recombination without homology used by mobile genetic elements: Which recombination type does not require long homologous sequences and is characteristically used by transposable elements that move about chromosomes?

Introduction / Context:
Mobile genetic elements move via specialized recombination mechanisms that differ from homologous recombination. Understanding these pathways explains how elements insert broadly and sometimes duplicate themselves during movement.

Given Data / Assumptions:

• Transposable elements can move without long sequence homology.
• Some transposons use a replicative mechanism, copying the element during transfer.
• The question targets the mechanism typical of mobile elements roaming chromosomes.

Concept / Approach:

Two non-homology pathways are commonly discussed: site-specific recombination (used by phage integrases at defined att sites) and replicative recombination (a transposition mechanism where a copy of the element is left behind and another inserts at a new site). The hallmark of many transposons is replicative recombination producing target site duplications and increased copy number.

Step-by-Step Solution:

Verification / Alternative check:

Classic models (e.g., Tn3) describe cointegrate formation and resolution, consistent with replicative recombination rather than simple cut-and-paste or att site integration.

Why Other Options Are Wrong:

Site-specific recombination is more typical of phage integration at specific att sites.

“Mutagenic recombination” is not a standard mechanistic category.

General recombination needs homology, which contradicts the prompt.

Common Pitfalls:

Conflating all non-homologous events; transposition often increases copy number (replicative) or moves by cut-and-paste, both distinct from phage att integration.

Final Answer:

Replicative recombination