Question

The function of DNA polymerase is

• A. It replaces RNA nucleotides with DNA nucleotides
• B. It fixes errors in the replication of DNA
• C. It adds nucleotides to the growing chain at the $3^{\prime }$ end.
• D. It is used in the polymerase chain reaction
• E. All of the above

Answer 1

Answer: (E)

All of the above

DNA polymerase I serve clean-up functions during replication, recombination, and repair. It has 3' to 5' proofreading exonuclease activity and 5' to 3' exonuclease activity. The 5' to 3' exonuclease activity of DNA polymerase I can replace an error containing a segment of DNA/RNA, paired to the template strand which is then simultaneously replaced by polymerase activity of the same enzyme. The process is called nick translation. DNA polymerase III is main DNA polymerising enzyme that has 5’ to 3’ polymerization and 3’ to 5’ exonuclease proofreading activities. PCR is a process of production of a large number of copies of a sample DNA using enzyme thermostable DNA polymerase.

Thus, the correct answer is option E.