Question

Choose the correct answer from the alternatives given :
The enzyme DNA dependent RNA polymerase catalyses the polymerisation reaction in ________ direction.

• A. Only 5 $\to$ 3
• B. Only 3 $\to$ 5
• C. Both (a) and (b)
• D. None of these

Answer 1

The correct option is A Only 5 $\to$ 3

The two strands have opposite polarity and the DNA-dependent RNA polymerase also catalyze the polymerization in only one direction, that is, 5 →→ 3, the strand that has the polarity 3 →→ 5 acts as a template, and is also referred to as template strand. The other strand which has the polarity 5 →→ 3 and the sequence same as RNA (except thymine at the place of uracil) is displaced during transcription. This strand (which does not code for anything) is referred to as coding strand.

So, the correct answer is 'Only 5 → 3'.