Question

Which of the following bacterial RNA polymerase subunits is found in the holoenzyme, but not the core enzyme?

A. Alpha (α)
B. Beta (β)
C. Sigma (σ)
D. Delta (δ)

Answer 1

The Sigma (σ) subunit is found in the holoenzyme of bacterial RNA polymerase but not in the core enzyme, playing a crucial role in transcription initiation by recognizing specific promoter regions.

Step-by-step explanation:

The bacterial RNA polymerase subunit that is found in the holoenzyme, but not in the core enzyme, is the Sigma (σ) subunit. In prokaryotic organisms such as E. coli, the RNA polymerase holoenzyme is responsible for transcription initiation and is composed of five subunits: two Alpha (α) subunits, one Beta (β) subunit, one Beta' (β') subunit, and the Sigma (σ) subunit. The core enzyme, which is responsible for the elongation phase of transcription, consists of all the subunits except for Sigma (σ). The Sigma (σ) subunit is critical for transcription initiation as it allows the RNA polymerase to recognize and bind to specific promoter regions on the DNA.