In prokaryotes, which mechanism correctly terminates transcription? Select the best answer, noting that bacteria use more than one termination pathway.

Introduction / Context:
Bacterial transcription termination occurs by two main mechanisms: rho-dependent termination, which requires the hexameric ATPase rho, and rho-independent (intrinsic) termination, driven by an RNA hairpin followed by a U-rich tract. Understanding these distinguishes transcription from translation signals.

Given Data / Assumptions:

• Stop and start codons regulate translation, not transcription.
• Poly(A) tails are hallmarks of eukaryotic mRNA processing, not bacterial termination.
• Rho protein can terminate certain transcripts by catching RNA polymerase.

Concept / Approach:
In rho-dependent termination, rho binds rut sites on nascent RNA, translocates along RNA using ATP, and disengages RNA polymerase at a paused site. This is a bona fide transcription termination pathway in bacteria.

Step-by-Step Solution:
Eliminate translation signals (stop/start codons, release factors) as unrelated to transcription termination.Eliminate eukaryotic-style polyadenylation as a termination trigger in bacteria.Identify rho as a valid bacterial termination factor.

Verification / Alternative check:
Biochemical assays show rho-dependent termination sensitivity to rho inhibitors and mutation of rut sites; intrinsic termination is observed with strong GC hairpins followed by U runs.

Why Other Options Are Wrong:
Stop/start codons are decoded by ribosomes. Poly(A) plays a different role in bacteria. Release factors act in translation termination, not transcription.

Common Pitfalls:
Conflating transcription termination with translation termination events occurring on the same polycistronic mRNA.

Final Answer:
Terminated by a protein called rho (ρ) in rho-dependent termination.