Which enzyme copies the original DNA to form a new strand?

Which enzyme copies the original DNA to form a new strand?

• A. DNA Ligase
• B. DNA Polymerase
• C. RNA Polymerase
• D. Helicase

Answer: (B)

Copying DNA during replication is carried out by DNA polymerase. This enzyme reads the existing (template) strand and adds complementary nucleotides to build a new strand in the 5′ to 3′ direction. A primer tethers the process so synthesis can begin, and DNA polymerase has proofreading activity to catch mistakes, improving fidelity. Although other enzymes play essential roles—helicase unwinds the double helix and ligase seals gaps between fragments, while RNA polymerase makes RNA (including the primers) rather than DNA copies—the task of copying the original DNA into a new strand is handled by DNA polymerase.

Copying DNA during replication is carried out by DNA polymerase. This enzyme reads the existing (template) strand and adds complementary nucleotides to build a new strand in the 5′ to 3′ direction. A primer tethers the process so synthesis can begin, and DNA polymerase has proofreading activity to catch mistakes, improving fidelity. Although other enzymes play essential roles—helicase unwinds the double helix and ligase seals gaps between fragments, while RNA polymerase makes RNA (including the primers) rather than DNA copies—the task of copying the original DNA into a new strand is handled by DNA polymerase.