During DNA replication, where do DNA polymerases add nucleotides?

DNA polymerases are crucial enzymes that play a central role in DNA replication by adding nucleotides to the growing DNA strand. They specifically add nucleotides to the 3'-OH (hydroxyl) end of the existing strand. This mechanism ensures that DNA synthesis proceeds in the 5' to 3' direction, meaning that nucleotides are continuously added to the 3' terminus of the new strand under synthesis.

The 3'-OH group acts as a reactive site that can form a phosphodiester bond with the 5'-phosphate group of an incoming nucleotide triphosphate. As a result, this directional synthesis is essential for the proper duplication of the genetic material during cell division and is consistent across all forms of life.

Furthermore, the role of the replication fork is to facilitate the unwinding of DNA strands to allow for the replication process, but it is not the specific location where nucleotides are added. Overall, the action of DNA polymerases adding nucleotides to the 3'-OH end of the growing strand is a fundamental aspect of how DNA is accurately replicated.