Question

Which of the following is responsible for adding nucleotides to the growing chain of DNA during replication?

• A. Ligase
• B. DNA polymerase
• C. Topoisomerase
• D. Both a and b

Answer 1

The correct option is B DNA polymerase

DNA replication is a process in which the parental strands get separated and new strands are synthesized complementary to each of the parental strand.
Several enzymes are involved in this process. However, once RNA primers are formed by enzyme primase, the 3’ OH end is available to add dNTPs further for elongation. The enzyme responsible for the addition of dNTPs complementary to the parental strand is DNA polymerase. In other words, it helps in polymerisation of the daughter strands in 5’$\to$ 3’ direction.
Ligase is the enzyme that helps to seal the nicks between sugar phosphate backbone.
Toposiomerase is an enzyme that helps to release the torsional strain generated in the DNA molecules due to supercoils.