Name and describe the two main termination mechanisms in bacterial transcription.

• A. Rho-dependent termination and rho-independent termination; rho helicase disrupts transcription after rut site; intrinsic terminator with GC-rich hairpin followed by U-rich tract causing RNA polymerase release.
• B. Termination by polyadenylation.
• C. Termination by ribosome dissociation.
• D. Termination when RNAP reaches telomeres.

Answer: (A)

Transcription termination in bacteria happens mainly through two strategies. One uses the Rho factor, a helicase that binds the growing RNA at a rut site and, fueled by ATP, moves along the transcript to catch up with RNA polymerase and destabilize the transcription complex, releasing the RNA. The other is Rho-independent termination, where the nascent RNA forms a GC-rich hairpin followed by a run of uracils; the pause and the weak RNA–DNA hybrid in this region promote dissociation and release of the transcript. The other options describe processes that aren’t how bacterial transcription ends—polyadenylation is a eukaryotic RNA processing step, ribosome dissociation is part of translation, and telomere-related termination isn’t involved in bacterial transcription.