Question

Which of the following properites of DNA polymerise necessitates the requirement of RNA primer in DNA replication?

• A. It gets denatured at high temperatures
• B. It can add a nucleotide only to a 5' end
• C. It can add a nucleotide only to a 3' end
• D. None of the above

Answer 1

The correct option is C

It can add a nucleotide only to a 3' end

DNA polymerase can add a nucleotide only to a free 3'-end. Thus, to start the replication reaction a free 3'-end is provided by the RNA primer as there is no free 3-end available for adding the first nucleotide. RNA primer is a short segment of RNA synthesized at the 5' end of DNA. It gives free 3' end for the polymerase to elongate the DNA.