Why does DNA polymerase need a primer?
Understand the Problem
The question is asking about the role of a primer in the function of DNA polymerase during DNA replication. It seeks to understand why a primer is necessary for this enzyme to initiate the synthesis of a new DNA strand.
Answer
DNA polymerase needs a primer to provide a starting point with a free 3' -OH group.
The DNA polymerase enzyme cannot initiate DNA synthesis on its own. It requires a primer, a short strand of RNA or DNA, to provide a starting point with a free 3' hydroxyl (-OH) group that the DNA polymerase can extend from by adding new nucleotides.
Answer for screen readers
The DNA polymerase enzyme cannot initiate DNA synthesis on its own. It requires a primer, a short strand of RNA or DNA, to provide a starting point with a free 3' hydroxyl (-OH) group that the DNA polymerase can extend from by adding new nucleotides.
More Information
DNA polymerases differ from RNA polymerases in that they can only add nucleotides to an existing strand, hence the requirement for a primer. In contrast, RNA polymerases can start synthesizing RNA from scratch.
Tips
A common mistake is to confuse the requirement of the primer for both DNA and RNA polymerases. Remember, only DNA polymerases need a primer.
Sources
- Primer Definition - Nature - nature.com
- Why dna polymerase require a primer but rna polymerase don't? - physicsforums.com
- Mechanism and Evolution of DNA Primases - NCBI - ncbi.nlm.nih.gov
