Gel electrophoresis is a group of techniques used by scientists to separate molecules based on physical characteristics such as size, shape, or isoelectric point. Gel electrophoresis is usually performed for analytical purposes, but may be used as a preparative technique to partially purify molecules prior to use of other methods such as mass spectrometry, PCR, cloning, DNA sequencing, or immuno-blotting for further characterization.
The first part, "gel", refers to the matrix used to separate the molecules. In most cases the gel is a crosslinked polymer whose composition and porosity is chosen based on the weight and composition of the target of the analysis. When separating proteins or small nucleic acids (DNA, RNA, or oligonucleotides) the gel is usually made with different concentrations of acrylamide and a cross-linker, producing different sized mesh networks of polyacrylamide. When separating larger nucleic acids (greater than a few hundred bases), the preferred matrix is purified agarose (which is a seaweed extract). In both cases, the gel forms a solid but porous matrix that looks and feels like clear Jell-O. Acrylamide, in contrast to polyacrylamide, is a neurotoxin and needs to be handled using Good Laboratory Practices (GLP) to avoid poisoning.
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