Which of the following statements best describes the termination of transcription in bacteria?

• A. Termination requires the addition of a 5' cap to the mRNA, signaling RNA polymerase to stop.
• B. Termination occurs when RNA polymerase reaches the end of the chromosome.
• C. Termination occurs when RNA polymerase encounters a specific DNA sequence that forms a hairpin loop in the RNA, causing the polymerase to dissociate.
• D. Termination is initiated by the binding of ribosomes to the mRNA, which signals the end of transcription.

Answer: (C)

Verified step by step guidance

1. Understand the process of transcription in bacteria: Transcription is the synthesis of RNA from a DNA template, carried out by RNA polymerase. It involves three main stages: initiation, elongation, and termination.
2. Focus on the termination stage: In bacteria, transcription termination occurs when RNA polymerase encounters specific signals in the DNA sequence that instruct it to stop synthesizing RNA.
3. Learn about the two main mechanisms of termination in bacteria: (1) Rho-dependent termination, which involves the Rho protein binding to the RNA and causing RNA polymerase to dissociate, and (2) Rho-independent termination, which involves the formation of a hairpin loop in the RNA followed by a stretch of uracil residues, destabilizing the RNA-DNA hybrid and causing RNA polymerase to release.
4. Analyze the statement about the hairpin loop: The correct answer describes Rho-independent termination, where a specific DNA sequence leads to the formation of a hairpin structure in the RNA. This structure disrupts the interaction between RNA polymerase and the DNA template, causing transcription to terminate.
5. Eliminate incorrect options: (1) The addition of a 5' cap is a feature of eukaryotic mRNA processing, not bacterial transcription termination. (2) RNA polymerase does not stop at the end of the chromosome; termination is sequence-specific. (3) Ribosome binding occurs during translation, not transcription termination.