Major types of electrophoresis

Electrophoresis is a term that describes both a concept and technique or experimental system. There are very many applications of electrophoresis and this technique is still finding new applications in a wide range of scientific disciplines. This section outlines the two major types of electrophoretic experimental systems that are commonly encountered by the bioanalytical chemist. 

A large number of variants of gel electrophoresis are used in bioanalytical analysis to allow separation and characterization of biomolecules, in particular nucleic acids (DNA, RNA) and proteins. The term gel refers to the matrix used to separate biomolecules, and in most cases is a cross-linked polymer. 

Both agarose and polyacrylamide gels are solid but porous matrices, which look and feel like clear jelly (Jell-0). These gels are prepared in different ways but both take the form of a slab (or alternatively column), cast like a jelly in a mould. While agarose gels are relatively easy to prepare, polyacrylamide gels are formed by complex polymerization and chemical cross-linking, and as such are usually purchased pre-cast. 

The study of molecular biology depends on the ability to separate soluble nucleic acid molecules according to their size. As such, agarose GE facilitates important DNA analyses and technologies including PCR, sequence analysis and cloning, and quantification of individual DNA species in a mixture. 

Polyacrylamide gel electrophoresis (PAGE) is fundamental to various biomolecu-lar techniques allowing separation of proteins and small fragments of nucleic acids. Arguably the most common use of this technique is in the study of proteins in mixtures and biological samples, separating different proteins into separate bands. 

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