Which enzyme is directly responsible for adding nucleotides during DNA replication?

Which enzyme is directly responsible for adding nucleotides during DNA replication?

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

Answer: (B)

DNA polymerase is the enzyme that directly adds nucleotides during DNA replication. It reads the template strand and uses deoxyribonucleoside triphosphates to synthesize a complementary new strand, forming phosphodiester bonds as it extends the chain in the 5' to 3' direction. It often has proofreading ability to catch and correct mistakes, helping ensure fidelity. Primers are required to start synthesis, and these are laid down by primase, an RNA polymerase, before DNA polymerase can extend the strand. On the leading strand, synthesis is continuous; on the lagging strand, it makes short fragments that are later joined by ligase. Helicase unwinds the double helix, and RNA polymerase (primase) makes the RNA primers. So, the enzyme that directly adds DNA nucleotides is DNA polymerase.

DNA polymerase is the enzyme that directly adds nucleotides during DNA replication. It reads the template strand and uses deoxyribonucleoside triphosphates to synthesize a complementary new strand, forming phosphodiester bonds as it extends the chain in the 5' to 3' direction. It often has proofreading ability to catch and correct mistakes, helping ensure fidelity. Primers are required to start synthesis, and these are laid down by primase, an RNA polymerase, before DNA polymerase can extend the strand. On the leading strand, synthesis is continuous; on the lagging strand, it makes short fragments that are later joined by ligase. Helicase unwinds the double helix, and RNA polymerase (primase) makes the RNA primers. So, the enzyme that directly adds DNA nucleotides is DNA polymerase.