The DNA-dependent RNA polymerase also catalyse the polymerisation in only one direction, that is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 5′ → 3′
During transcription, the enzyme DNA-dependent RNA polymerase joins nucleotides one by one to make an RNA chain. It adds each new nucleotide to the 3′ end of the growing chain, so the chain grows from the 5′ end towards the 3′ end. It works in this one direction only.
(1) 5′ → 3′ — Correct. This is the only direction of polymerisation. Because of it, the DNA strand with the polarity 3′ → 5′ acts as the template strand.
(2) 3′ → 5′ — Incorrect. This is the polarity of the template strand that is read, not the direction in which RNA is made.
(3) 3′ → 3′ — Incorrect. It is not a direction of any nucleic acid chain. A chain has a 5′ end and a 3′ end.
(4) 5′ → 5′ — Incorrect. It is also not a direction of any chain.
Note: A similar question was also asked in CUET (UG) 2026 on 29-05-2026 (Slot 1).
NCERT Extract:
Transcription Unit – …
