During transcription, in which direction does RNA polymerase move along the DNA template strand?

• A. It moves along the template strand in the $3\prime \to 5\prime$ direction.
• B. It moves along the coding strand in the $3\prime \to 5\prime$ direction.
• C. It moves bidirectionally from the promoter in both $5\prime \to 3\prime$ and $3\prime \to 5\prime$ directions.
• D. It moves along the template strand in the $5\prime \to 3\prime$ direction.

Answer: (A)

Verified step by step guidance

1. Recall that during transcription, RNA polymerase synthesizes RNA by reading the DNA template strand.
2. Understand that DNA strands have directionality, labeled as 5' to 3' and 3' to 5', which is crucial for enzyme movement and synthesis.
3. Know that RNA polymerase moves along the DNA template strand in the 3' to 5' direction to synthesize the RNA strand in the 5' to 3' direction.
4. Recognize that the template strand is complementary and antiparallel to the RNA being synthesized, while the coding strand has the same sequence as the RNA (except T is replaced by U).
5. Therefore, RNA polymerase moves along the template strand in the 3' to 5' direction, ensuring the RNA is synthesized in the correct 5' to 3' direction.