Question

On average, errors occur in DNA synthesis only once in every ten billion nucleotides incorporated. Which of the following does NOT contribute to this high fidelity of DNA synthesis? (A) Complementary base-pairing between the nucleotides (B) Tightening of the DNA polymerase around its active site to ensure correct pairing before monomer incorporation (C) Proofreading by the 3'-to-5' exonuclease activity of the enzyme to correct mispairing even after monomer incorporation (D) A strand-directed mismatch repair system that detects and resolves mismatches soon after DNA replication (E) None of the above

Answer 1

Answer:

(E) None of the above

Explanation:

All of the answers contribute to the high fidelity of DNA synthesis.

Accuracy of the DNA replication is achieved thanks to various mechanisms such as:

• DNA polymerase activity (high processivity)-ability of the enzyme to copy long stretches of DNA
• DNA polymerase proofreading-ability to recognize its own mistakes and fix them
• Cell's surveillance-cell monitors its DNA status, checks for the damage
• Mismatch Repair-cell contain repair machinery which recognizes DNA helix deformities,  removes and replaces the portion containing the mismatch etc.