DNA Structure and Replication

ID #1711

You said that Polymerase I recognizes RNA bases and replaces them with DNA bases. Doesn't the phrase "recognizes RNA bases" means that it uses RNA as the template? Wouldn't that make polymerase I an RNA dependent, DNA synthesizing enzyme? Can you please explain?

In that context, when I said that DNA polymerase I recognizes the RNA bases in the primer, I just meant that it recognized that they weren't supposed to be there. When determining if a nucleic acid synthesizing enzyme is "RNA dependent" or "DNA dependent," you have to ask what the template molecule is that is being read in order to "know" what the next base is supposed to be. When DNA polymerase I removes an RNA base (let's say guanine, for example), it doesn't automatically bring in a dGTP. It has to check the template first and determine what the appropriate base is supposed to be. It's not "checking" the RNA that it's removing; it's checking the single-stranded DNA template, making it DNA dependent.

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