R plasmids terminology: Plasmids that carry both the resistance transfer factor (RTF) and resistance (r) determinants are termed what?

Introduction / Context:Antibiotic resistance plasmids (R plasmids) may have two functional parts: an RTF region that mediates transfer and an r-determinant region encoding resistance genes. Terminology distinguishes whether a plasmid can self-transfer.

Given Data / Assumptions:

• RTF provides conjugation (transfer) functions.
• r determinants encode resistance phenotypes.
• Presence of both implies self-transmissibility.

Concept / Approach:

If a plasmid carries both RTF and r determinants, it can transfer itself by conjugation and confer resistance to recipients. Therefore it is a conjugative plasmid. Plasmids lacking transfer functions are non-conjugative and require “helper” plasmids.

Step-by-Step Solution:

Verification / Alternative check:

Mating experiments show such plasmids mobilize themselves and often co-mobilize other plasmids lacking transfer regions if oriT is present.

Why Other Options Are Wrong:

“Non self-transmissible” and “non-conjugative” contradict the presence of RTF.

“None of the above” is incorrect because an established term exists.

Common Pitfalls:

Confusing conjugative R plasmids with mobilizable plasmids; the latter have oriT but need transfer functions in trans.

Final Answer:

Conjugative plasmids