DNA polymerase

DNA polymerases are enzymes that synthesize DNA by adding nucleotides to a growing strand, usually copying an existing DNA strand. Different polymerases perform replication, repair, and specialized DNA synthesis.

DNA replication: The process by which a cell copies its DNA before division. DNA polymerases build the new strands that make genome duplication possible.
Deoxyribonucleotide: A nucleotide containing deoxyribose that serves as a building block of DNA. DNA polymerases incorporate these substrates into a growing DNA strand.
Polymerase chain reaction: A laboratory method that repeatedly copies selected DNA regions through cycles of heating and cooling. PCR uses a heat-stable DNA polymerase to amplify DNA outside cells.
Arthur Kornberg: An American biochemist who discovered and purified DNA polymerase I from Escherichia coli. His work identified the first known DNA-synthesizing enzyme and earned him the 1959 Nobel Prize in Chemistry.
RNA polymerase: An enzyme that synthesizes RNA using a DNA or, in some cases, RNA template. RNA polymerases make RNA rather than extending a DNA product.
DNA polymerase proofreading: The removal of a mismatched nucleotide by a DNA polymerase’s exonuclease activity during DNA synthesis. Some polymerases reverse direction to remove errors before continuing strand extension.
Phosphodiester bond: A covalent bond linking the sugar of one nucleotide to the phosphate of another in a nucleic acid chain. Each addition creates this bond in the DNA backbone.
Taq polymerase: A thermostable DNA polymerase isolated from the bacterium Thermus aquaticus. Its heat tolerance made repeated high-temperature PCR cycles practical.
DNA polymerase I: An Escherichia coli enzyme that synthesizes DNA and also has exonuclease activities. This was the enzyme Kornberg isolated in his pioneering studies of DNA synthesis.
Primase: An enzyme that synthesizes short RNA primers on a DNA template. Primase can start a new chain, whereas most DNA polymerases require a pre-existing 3′ end.

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