What is the correct term for transfer of genetic material between bacteria that are in direct physical contact via a mating bridge (pilus)?

Introduction / Context:
Bacteria exchange genes through several mechanisms. Direct, pilus-mediated DNA transfer between two living cells is a hallmark of conjugation. Mastering these terms is crucial in microbial genetics and antimicrobial resistance studies.

Given Data / Assumptions:

• Cells are in direct contact.
• DNA passes through a conjugative pilus or mating channel.
• Donor typically carries a conjugative plasmid (e.g., F factor).

Concept / Approach:
Conjugation requires tra genes that assemble the mating apparatus. DNA is nicked at oriT and transferred as a single strand, then replicated in both donor and recipient. Transformation, by contrast, involves uptake of free DNA from the environment; transduction involves bacteriophages; replication is DNA duplication within a cell.

Step-by-Step Solution:

Verification / Alternative check:
Classic E. coli F+ to F− mating experiments and HFr mapping confirm the definition of conjugation.

Why Other Options Are Wrong:

• Transformation: Involves competent cells taking up naked DNA; no contact needed.
• Transduction: DNA moved by phage particles, not direct contact.
• Replication: DNA duplication inside a cell, not gene transfer between cells.

Common Pitfalls:

• Using “lysogeny” or “transduction” interchangeably with conjugation.
• Forgetting that conjugation typically needs conjugative genes on a plasmid or integrated element.

Final Answer:
Conjugation