Final answer:
DNA polymerase is the enzyme responsible for adding nucleotides to the 3' hydroxyl of a growing DNA strand during DNA replication. It extends the primer by adding nucleotides complementary to the template strand and forming phosphodiester bonds, using energy from nucleotide triphosphates.
Step-by-step explanation:
The Role of DNA Polymerase in DNA Replication
The enzyme that catalyzes the addition of nucleotides to the 3' hydroxyl of a growing DNA strand is DNA polymerase. This enzyme is essential during the DNA replication process. DNA polymerase synthesizes the new DNA by adding nucleotides that are complementary to the template strand to the 3' end of the primer. This addition of nucleotides to the new strand is a critical part of the elongation phase of DNA synthesis.
DNA polymerase requires the help of a primer, which provides the free 3'-OH end, to begin synthesis. The primer is typically a short RNA strand synthesized by RNA primase. Once the primer is in place, DNA polymerase extends it, adding nucleotides sequentially and forming phosphodiester bonds. These bonds are formed between the phosphate of a nucleotide triphosphate and the 3' OH end of the existing chain. The energy needed for this process comes from the cleavage of the high-energy phosphate bonds in the nucleotide triphosphates.
In prokaryotic organisms, such as bacteria, DNA polymerase III is the primary enzyme for synthesizing new DNA strands, while DNA polymerases I and II are mainly involved in DNA repair mechanisms. These enzymes ensure the accuracy of DNA replication, contributing to the preservation of genetic information across generations.