Question

A mutation occurs in the gene encoding the enzyme DNA polymerase of a eukaryotic cell. Which of the following events of DNA replication would not occur?

• A. The DNA helix would not unwind properly for replication.
• B. The DNA helix would not be held apart so that it could be replicated by DNA polymerase.
• C. An RNA primer would not be generated so that DNA replication could begin.
• D. Complementary nucleotides would not be paired with the template strands.
• E. The Okazaki fragments on the lagging strand of DNA would not be joined together correctly.

Answer 1

Answer: (D)

Complementary nucleotides would not be paired with the template strands.

DNA polymerase is the enzyme that catalyse the synthesis of DNA and are of two types: template dependent and template independent. Template dependent DNA polymerases are further of two types, DNA dependent DNA polymerases and RNA dependent DNA polymerases. DNA dependent DNA polymerase which is simply called as DNA polymerase synthesises a new strand of DNA on a DNA template whereas RNA dependent DNA polymerase which is also called as reverse transcriptase, synthesises a new strand of DNA on a RNA template. DNA polymerase pairs the complementary nucleotides with the template strand which are then joined by DNA ligase. Hence, if mutation occurs in a gene encoding for DNA polymerase, then DNA polymerase will not work and DNA synthesis will not occur.

So, the correct answer is 'Complementary nucleotides would not be paired with the template strands'.