What is the function of a transcription terminator?

• A. To signal RNA polymerase to stop transcription, defining transcript boundaries and stability.
• B. To start transcription.
• C. To replicate plasmid.
• D. To enhance translation.

Answer: (A)

Transcription terminators serve to stop RNA polymerase and end the transcript at a defined point. This termination creates clear transcript boundaries and helps ensure the RNA is released in a usable form, contributing to proper mRNA stability and processing. In bacteria, termination can occur through two main mechanisms: rho-independent termination, which uses a hairpin structure in the nascent RNA followed by a run of uracils to cause dissociation, and rho-dependent termination, where the Rho helicase catches up to the polymerase and prompts release. Terminators are not involved in starting transcription (that’s the promoter’s job), they don’t duplicate plasmids, and they don’t directly enhance translation, which depends on ribosome binding and initiation signals on the mRNA.