What is the primary function of DNA polymerase during DNA replication?

What is the primary function of DNA polymerase during DNA replication?

• A. Adds complementary nucleotides to synthesize a new DNA strand
• B. Unwinds the DNA double helix
• C. Seals breaks in the sugar-phosphate backbone
• D. Synthesis of RNA primers

Answer: (A)

DNA polymerase is the enzyme that builds the new DNA strand by adding nucleotides that pair with the template strand. It reads the template and places the correct complementary base (A with T, G with C), forming a phosphodiester bond to extend the growing strand in the 5' to 3' direction. It can’t start a strand from nothing, which is why a short RNA primer is required to provide the starting point for synthesis. As it adds nucleotides, polymerase also proofreads to catch and correct misincorporations. Other enzymes do separate tasks: helicase unwinds the double helix, primase lays down the RNA primer, and ligase seals any remaining nicks after primer removal.

DNA polymerase is the enzyme that builds the new DNA strand by adding nucleotides that pair with the template strand. It reads the template and places the correct complementary base (A with T, G with C), forming a phosphodiester bond to extend the growing strand in the 5' to 3' direction. It can’t start a strand from nothing, which is why a short RNA primer is required to provide the starting point for synthesis. As it adds nucleotides, polymerase also proofreads to catch and correct misincorporations. Other enzymes do separate tasks: helicase unwinds the double helix, primase lays down the RNA primer, and ligase seals any remaining nicks after primer removal.