Question

Which is NOT the function of sigma 3.2?

A. Pulls DNA template into the active center (scrunching)

B. Positions the first nucleotide in nascent RNA

C. Facilitates promoter clearance by RNAP (displacement by the nascent RNA)

D. Blocks exit channel for the RNA

Answer 1

Sigma 3.2 D. does not function to block the exit channel for RNA; rather, it aids RNA polymerase in transcription initiation and promoter clearance.

Step-by-step explanation:

The correct answer to the question Which is NOT the function of sigma 3.2? is D. Blocks exit channel for the RNA. The sigma 3.2 refers to a component of the sigma factor 70, which is part of the bacterial RNA polymerase holoenzyme. Its role during transcription initiation includes facilitating the opening of the DNA double helix, allowing RNA polymerase to create an initial RNA transcript. Once transcription initiation is complete, sigma 3.2 helps in promoter clearance, enabling the RNA polymerase to leave the promoter and proceed with transcript elongation. Therefore, blocking the exit channel for the RNA would not be a function of sigma 3.2 as it facilitates RNA polymerase's progression rather than hindering it.

The function of sigma 3.2 is to facilitate promoter clearance by RNAP (displacement by the nascent RNA). This means that sigma 3.2 helps in the process of clearing the promoter region on the DNA so that RNA polymerase can begin transcribing the DNA into RNA. This is an important step in gene expression.