Question

In the transition from abortive cycling to elongation of transcription, which is TRUE?

A. Sigma loses affinity for the promoter DNA and RNAP core, and pressure of the growing RNA chain dislodges sigma from the RNA exit pore.

B. DNA scrunching contributes to a stronger binding between RNAP core and sigma 3.2 subdomains.

C. The wall separates RNA transcript from DNA template, thus facilitating abortive cycling.

D. Sigma 1.1 subdomain pretends to be a promoter and confuses RNAP, which loses its mind, does not know what to do, and aborts transcription.

Answer 1

A is true: Sigma factor dissociates from RNAP and DNA, allowing the RNA polymerase to transition from abortive cycling to elongation. B, C, and D are not accurate representations of the transcription process.

Step-by-step explanation:

The correct option is A:

The transition from abortive cycling to elongation of transcription is properly described by the statement A: Sigma loses affinity for the promoter DNA and RNAP core, and pressure of the growing RNA chain dislodges sigma from the RNA exit pore. During the early stages of transcription, sigma factors are essential for guiding RNA polymerase to the correct promoter regions. However, once the RNA polymerase begins elongation, the sigma factor is no longer needed, and it dissociates from the RNA polymerase core as well as the DNA template.

The process of transcription includes initiation, where RNA polymerase binds to the promoter with the help of a sigma factor; elongation, where the RNA strand is extended; and termination, where the transcript is released, typically after encountering specific terminator sequences.

Answer choices B, C, and D offered incorrect or fictitious scenarios regarding transcription mechanisms, which do not align with the established biology of transcription.