Question

Which of the following is not an enzyme involved in DNA replication?

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

Answer 1

The correct option is D RNA primer

RNA primer is a short segment of nucleotides (about 5-10 nucleotides in length) which are the first few bases added by the enzyme RNA primase at the beginning of DNA replication, to the point where the double helix has unzipped. RNA primers are necessary because the main enzyme that adds nucleotides, DNA polymerase, can only add nucleotides to an already existing strand of nucleotides. Thus, the RNA primer basically serves to prime or prep, and lay a foundation for DNA synthesis. DNA polymerase then takes over by adding nucleotides, beginning with the 3’ end of the RNA primer (in the 5’$\to$ 3’ direction).