Question

A geneticist finds that a strain of bacteria to produces a non-functional sigma factor. Which among the following steps in transcription would most likely be first affected?
A.Assembly of RNAP onto the DNA strand

B.Identification and binding of RNAP on to the promoter sequence

C.Conversion of open initiation complex to closed initiation complex

D.Synthesis of RNA after the formation of open initiation complex

Answer 1

Answer:

The correct answer is - B. Identification and binding of RNAP onto the promoter sequence.

Explanation:

Bacterial RNA polymerases have subunits known as Sigma factors responsible for the identification and specificity of promoter binding of RNAP and regulate the efficiency of RNA synthesis during transcription is initiated.

These bacteria producing the nonfunctional subunits of RNA polymerase or sigma factor will be unable to identify and tightly bind to promoter elements that are RNAP.