Why is RNA polymerase used in the DNA replication?

1 Answer
Jul 31, 2016


Technically it isn't. RNA polymerase is used in DNA transcription.


Several terms are often confused when talking about this subject, so allow me to explain the difference between replication and transcription and DNA and RNA polymerases.

Replication vs. transcription
The difference is in whether the purpose is to make DNA or RNA:

  • Replication = making DNA from DNA; in this case all the DNA is copied for the purpose of creating new cells (cell division)
  • Transcription = making mRNA from DNA; this is when a small part of the DNA (gene) is needed to make a protein.

RNA polymerase vs. DNA polymerase
In general polymerases are enzymes that are able to make long strings of nucleotides (the building blocks of genetic material). There are two main polymerases:

  • DNA polymerase = the enzyme that makes DNA from DNA
  • RNA polymerase = the enzyme that makes RNA from DNA

RNA polymerase does not play a role in DNA replication, it plays a role in DNA transcription. RNA polymerase makes mRNA from DNA.

Note that enzymes that replicate RNA are called RNA replicases. In line with this it would make sense to call DNA polymerase, DNA replicase. This is technically correct, but the term is rarely used.