Question

What is the target of the nucleophilic attack in the DNA polymerase mechanism?

a) 3' hydroxyl group
b) 5' phosphate group
c) 2' hydroxyl group
d) 3' phosphate group

Answer 1

The target of the nucleophilic attack in the DNA polymerase mechanism is the alpha-phosphorus atom of the incoming nucleotide triphosphate, attacked by the 3' hydroxyl group of the growing nucleotide chain, leading to the formation of a phosphodiester bond.

Step-by-step explanation:

The target of the nucleophilic attack in the DNA polymerase mechanism is the alpha-phosphorus atom of the incoming nucleotide triphosphate (NTP). The nucleophile in this reaction is the 3' hydroxyl (3'-OH) group of the growing nucleotide chain.

During DNA synthesis, the 3'-OH group attacks the alpha-phosphorus atom, leading to the formation of a new phosphodiester bond and the release of a pyrophosphate molecule (PP).

DNA polymerases require divalent metal ions like Mg2+ to properly position the nucleophile for the attack, ensuring successful DNA synthesis. Additionally, DNA polymerases work in the 5' to 3' direction, synthesizing new strands that are complementary to the template strands.