Question

The enzyme responsible for synthesizing RNA primers during DNA replication is -

• A. DNA polymerase
• B. Primase
• C. Topoisomerase
• D. Helicase

Hint:

Remember the key limitation of DNA polymerase: it's an extender, not a starter. It needs a "primer" to get started. The enzyme that makes this primer is appropriately named \textbf{Primase}.

Answer 1

The Correct Option is B

Step 1: Concept Overview:
The question requires identifying the enzyme responsible for creating the short RNA primers that initiate DNA synthesis during replication.
Step 2: Enzyme Roles in Detail:
Reviewing the roles of key enzymes in DNA replication:

Helicase: Unwinds the DNA double helix at the replication fork, separating strands to serve as templates.
Primase: An RNA polymerase that synthesizes short RNA primers (5-10 nucleotides) complementary to the DNA template. These primers provide the 3'-OH group needed for DNA polymerase to begin synthesis.
DNA polymerase: The primary replication enzyme. It adds deoxynucleotides to the 3' end of the RNA primer, building the new DNA strand. It also proofreads and replaces RNA primers with DNA.
Topoisomerase (or DNA gyrase in bacteria): Relieves torsional strain and supercoiling ahead of the replication fork.
Step 3: Conclusion:
Primase is the enzyme responsible for synthesizing RNA primers.