What distinguishes DNA polymerase from RNA polymerase?

DNA polymerase is distinct from RNA polymerase primarily because it requires a primer to initiate the synthesis of new DNA strands. This is essential for DNA replication, where DNA polymerase synthesizes a new strand by adding nucleotides complementary to the template strand. The primer, which is typically a short RNA segment, provides a free 3' hydroxyl (OH) group that DNA polymerase needs to start the elongation process.

In contrast, RNA polymerase is capable of initiating RNA synthesis de novo, meaning it does not require a primer to start the synthesis of RNA. It can bind to specific regions on the DNA template and begin synthesizing RNA directly. This fundamental difference in initiation of synthesis is what primarily sets DNA polymerase apart from RNA polymerase.