Identify the regions of the transcription unit.
(A) Promoter
(B) Sigma factor
(C) Terminator
(D) The structural gene
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (C) and (D) only
(A) Promoter — Correct. The promoter lies upstream (at the 5' end of the coding strand) and is where RNA polymerase binds.
(B) Sigma factor — Incorrect. The sigma (σ) factor is a protein that helps RNA polymerase start transcription; it is not a part of the DNA.
(C) Terminator — Correct. The terminator lies downstream and marks where transcription ends.
(D) The structural gene — Correct. It lies between the promoter and terminator and is the part that is transcribed.
Note: A similar question was also asked in CUET (UG) 2026 on 18-05-2026 (Slot 1).
NCERT Extract:
Transcription Unit – “A transcription unit in DNA is defined primarily by the three regions in the DNA : (i) A Promoter (ii) The Structural gene (iii) A Terminator There is a convention in defining the two strands of the DNA in the structural gene of a transcription unit.”