Cell Technology: Polyacrylamide Gel
By Melanie D.
Electrophoresis is a method of separating proteins and nucleic acids. This method works by applying a constant voltage to a small container of gel in which proteins or nucleic acids are placed. In the gel, there are small pockets where the stained material is placed. In order to separate the material, the material must be charged. The charged material is attracted to the side of the container that has the opposite charge. This attraction pulls the material towards that side, in the gel, and begins to separate. The material separates in the gel because with a constant charge running through the gel, all the material is being pulled the same amount. Because different parts of the different materials being tested have different masses, those parts move at different speeds. The parts also have slightly different charges, which causes them to be attracted at slightly different rates. As the currents run through the gel, the nucleic acids or proteins move along slowly to the other side of the gel at different speeds. Because the material is dyed, the location of each different part of the material is visible as small rings of color on a clearish gel.
The separating of DNA has many important purposes. By running two sets of DNA through the gel next to each other, it can be determined if a person is the parent of a child, since the rings of DNA would match up. By comparing a map of the DNA, it can also be determined if a suspected criminal's DNA matches the DNA found at the crime scene. This information could be important evidence at a trial. Perhaps the reason why many people know about DNA testing is because of its publicity during the O.J. Simpson trial. DNA testing can also be used for comparing DNA samples and finding similarities by running different DNAs with the same restriction enzyme and seeing where the enzyme cut the DNA.
Polyacrylamide gel electrophoresis is just one of the many different ways to separate materials, but this method has and will continue to be an important contributor to cytology and to the world around us.
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