Question

Which one is correct about transcription ?

• A. 5'-OH group joins with 3'-triphosphate group
• B. RNA polymerase II enzyme needs no primer
• C. RNA chain grows in 3' → 5' direction
• D. Only the coding strand (sense strand) of DNA is transcribed

Hint:

RNA polymerase differs from DNA polymerase in one key requirement for starting synthesis.

Answer 1

The Correct Option is B

Step 1: Go through each option against the known mechanics of transcription. New nucleotides are added by linking the incoming nucleotide's 5'-triphosphate to the growing chain's existing 3'-OH end, so describing it the other way around, as in option (A), is incorrect.

Step 2: RNA synthesis always proceeds 5' to 3', matching every other nucleic acid polymerization process in the cell, so option (C), which claims 3' to 5' growth, is false.

Step 3: RNA polymerase actually reads the DNA template strand, and the RNA product ends up matching the coding (sense) strand in sequence, meaning the coding strand itself is not the one being transcribed, so option (D) is false too.

Step 4: The one genuinely accurate statement is that RNA polymerase II, unlike DNA polymerases, can initiate a new strand without requiring a primer, which is option (B).