Question

Which of the following statements is true with respect to transcription?

• A. RNA synthesis always occurs in the 5' - 3' direction
• B. RNA polymerase needs a primer to initiate transcription
• C. U is inserted in RNA complementary to T in DNA
• D. All of these

Answer 1

The correct option is A RNA synthesis always occurs in the 5' - 3' direction

Transcription is a process by which the genetic information from one of the strands of DNA (template) is copied on to mRNA.

The enzyme required for copying genetic information from one strand of DNA into RNA (transcription) is DNA dependent RNA polymerase.

DNA-dependent RNA polymerase catalyses the polymerisation in only one direction, that is, 5'→3', using the DNA strand that has the polarity 3'→5', i.e., using the template strand.

Hence, RNA synthesis always occurs in the 5' - 3' direction.


Unlike DNA synthesis, a primer is not needed for initiating synthesis of a new RNA strand.

RNA contains U instead of T, and U base pairs with A.
Hence, U is inserted in RNA complementary to A in the DNA template.