DNA Polymerase vs. RNA Polymerase — What's the Difference?

DNA Polymerase is an enzyme that plays a vital role in DNA replication. Its primary function is to synthesize new DNA strands by adding nucleotides in a sequence determined by a DNA template strand. This ensures that genetic information is accurately passed on during cell division. In contrast, RNA Polymerase is responsible for the process of transcription, where it reads the DNA sequence and synthesizes a complementary RNA strand, forming the precursor of mRNA, tRNA, or rRNA.

In the cellular context, DNA Polymerase acts during the S-phase of the cell cycle when DNA replication occurs, ensuring that each daughter cell receives a complete set of genetic information. RNA Polymerase, however, functions throughout the cell cycle, transcribing genes as needed to regulate cellular processes and respond to environmental cues.

Focusing on their activities, DNA Polymerase not only synthesizes new DNA strands but also possesses proofreading abilities. If an incorrect nucleotide is added, this enzyme can detect the mistake and replace it, ensuring the fidelity of DNA replication. On the other hand, RNA Polymerase lacks this proofreading capability, making RNA synthesis more error-prone compared to DNA replication.

In terms of structure and types, there are several forms of both DNA Polymerase and RNA Polymerase. Various types of DNA Polymerases function in DNA replication and repair, with some specialized for leading and lagging strand synthesis. Conversely, in eukaryotes, there are three main types of RNA Polymerase (I, II, III), each responsible for transcribing different types of RNA molecules.