Summary
The enzyme that adds nucleotides to a growing DNA strand in the 5 prime to 3 prime direction.
In depth
It adds nucleotides to a free 3' OH and needs a primer. It checks each base pair and has 3' to 5' exonuclease activity to remove mistakes (proofreading). E. coli has five DNA polymerases; Pol III replicates and Pol I removes primers. Eukaryotes use Pol alpha, delta and epsilon.
Polymerases can only synthesise 5' to 3'.
Bacterial DNA polymerase III is the main replicating enzyme and polymerase I removes primers and fills gaps; eukaryotes use Pol alpha (with primase), Pol delta (lagging strand) and Pol epsilon (leading strand), with specialised translesion polymerases that bypass damage at the cost of accuracy. The processivity of a replicative polymerase depends on a sliding clamp.
Thermostable Taq polymerase from Thermus aquaticus (a hot-spring bacterium) made PCR practical because it survives heating to 95 degrees. Kary Mullis received the 1993 Nobel Prize for PCR. Proof-reading mutants of polymerase epsilon cause hypermutated cancers.
Key idea: polymerases add nucleotides only to a 3 prime end, so DNA is always synthesised in the 5 prime to 3 prime direction.
Frequently asked questions
What is DNA Polymerase?
The enzyme that adds nucleotides to a growing DNA strand in the 5 prime to 3 prime direction.
Which area of biology covers DNA Polymerase, and how advanced is it?
DNA Polymerase is one of the 52 topics in Molecular Biology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Primase and RNA Primer, Okazaki Fragments, Leading and Lagging Strands.
Can you give an example of DNA Polymerase?
Taq polymerase is heat stable and used in PCR.
What should I learn before DNA Polymerase?
Work through the Beginner topics in Molecular Biology first, such as Central Dogma, DNA Replication, Base Pairing, then return to DNA Polymerase. Intermediate topics assume the Beginner vocabulary.
What topics are related to DNA Polymerase?
The closest topics to DNA Polymerase are Primase and RNA Primer, Okazaki Fragments, Leading and Lagging Strands, RNA Polymerase. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand DNA Polymerase?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for DNA Polymerase. To practise the whole of Molecular Biology, use the Molecular Biology quiz.
How is DNA Polymerase different from Primase and RNA Primer?
DNA Polymerase: The enzyme that adds nucleotides to a growing DNA strand in the 5 prime to 3 prime direction. Primase and RNA Primer: Primase lays down a short RNA primer that gives DNA polymerase a starting 3 prime end. Read both side by side and note what each one explains.
How should I study DNA Polymerase step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Primase and RNA Primer and explain the difference aloud. Finally, take the Molecular Biology quiz and come back to this page for any question you miss.