Question

Which of the following is an accurate description of the polymerization reaction leading to DNA polymerization? a. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.

b. The 5'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.
c. The 3'-hydroxyl group at the end of the primer executes an electrophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.
d. The 5'-hydroxyl group at the end of the primer executes an electrophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.
e. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-γ-phosphate of the incoming nucleotide triphosphate.

Answer 1

The correct description of the DNA polymerization reaction is that the 3'-hydroxyl group at the end of the primer attacks the 5'-alpha-phosphate of the incoming nucleoside triphosphate, leading to the formation of a phosphodiester bond and extension of the DNA chain in a 5' to 3' direction. The correct option is a. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.

Step-by-step explanation:

An accurate description of the polymerization reaction leading to DNA polymerization is (a) The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate. This is because DNA polymerization involves the formation of phosphodiester bonds, where the 3'-OH group of the growing nucleotide chain acts as a nucleophile to attack the α-phosphorous of the incoming nucleotide triphosphate (NTP). The reaction is initiated with the 3'-OH group at the end of the primer and results in the extension of the DNA chain in the 5' to 3' direction. The pyrophosphate (PP), which serves as the leaving group, is released and subsequently broken down into inorganic phosphates, driving the polymerization process forward.

The correct option is a. The 3'-hydroxyl group at the end of the primer executes a nucleophilic attack on the 5'-α-phosphate of the incoming nucleotide triphosphate.