Question

What is the function of RNAP Clamp/Jaws?

A. Causes DNA bend; bending of DNA helps melt the strands and flip bases in the template strand to be accessible

B. Changes its conformation with each cycle of new nucleotide addition and keeps in contact with the growing RNA strand

C. Blocks exit of the nascent RNA transcript and separates it from DNA template

D. Clamp is initially out of position; after DNA has melted, it gets repositioned to keep DNA in the active site tighter

Answer 1

The RNAP clamp, often called jaws, is repositioned after the DNA strands are separated (melted) to keep the DNA in the active site for efficient transcription. It is distinct from the sliding clamp role in DNA replication, which holds DNA polymerase in place as it adds nucleotides.

Step-by-step explanation:

The function of the RNAP (RNA Polymerase) clamp, often referred to as the jaws, is a crucial aspect of the transcription process. Answer choice D is the most accurate description of its function. The RNAP clamp is initially positioned away from the DNA. Once the DNA has melted, meaning the two strands have been separated, the clamp repositions itself so that it can maintain a tight interaction with the DNA. This repositioning of the clamp keeps the DNA securely in the active site, ensuring that transcription can occur efficiently as the RNA polymerase moves along the DNA template.

While DNA polymerase is the main enzyme responsible for nucleotide addition during DNA replication, the RNAP clamp has a different role during transcription. The sliding clamp in DNA replication and the RNAP clamp in transcription are both important in their respective processes for holding polymerase enzymes in place, but they are functionally distinct proteins.