Answer: DNA polymerase can only add nucleotides to an existing 3 prime OH end.
- A DNA polymerase is unable to unwind the double helix without a primer present
- B DNA polymerase can only add nucleotides to an existing 3 prime OH end
- C Primers are required to supply the chemical energy needed for replication
- D Primers function to protect newly synthesized DNA strands from nucleases
Correct answer: B. DNA polymerase can only add nucleotides to an existing 3 prime OH end
Explanation: DNA polymerase cannot initiate synthesis on a bare template; it can only extend an existing strand with a free 3 prime OH, which the RNA primer provides.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.