Virtual Lab 1: Polymerase Chain Reaction - Introduction
The technique of Polymerase Chain Reaction (PCR) 聚合酶鏈鎖反應 was invented by Dr. Kary Banks Mullis in 1983. He obtained the Nobel Prize in Chemistry for conceiving PCR technology in 1993. The basic principle of PCR is described as follows:
A small amount of DNA containing the target gene was placed in a tube and denatured. A pair of primers which are short DNA segments matching each side of the desired gene are added to the tube. The primers then match with specific sequence on the DNA. Following the addition of nucleotides and DNA polymerase, new DNA strands are synthesized.
Different temperatures are required for DNA denaturation, binding of primers and DNA synthesis. Hence, the PCR tube is being heated and cooled manually. Since DNA polymerase is denatured at high temperature during DNA denaturation, it needs to be added in each cycle. This is time consuming and labor intensive.
To automate the PCR process, a semi-automated thermocycling 熱循環 machine “Mr. Cycle” was invented in 1985 but fresh enzyme still needed to be added to replace the heat damaged enzymes in each cycle. Later, scientists try to make use of Taq polymerase in PCR. It is extracted from bacterium Thermus aquaticus which grows in hot pools near volcanic vent and hence the enzyme will not denature at 95oC. The first automated thermal cycler was created in 1988.
Go to the virtual lab and try to amplify DNA using PCR