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Subject - Biochemistry

Electrophoresis is the movement of dissolved ionic compounds in an electrical field. Particles with a positive charge move toward the cathode, those with a negative charge to the anode. Because many biologically significant molecules (e.g. amino acids, proteins, nucleic acids, lipids) contain ionic groups, electrophoretic separation techniques are extremely important for both preparatory and analytical processes in biochemistry and molecular biology.

It is possible to carry out electrophoresis in a free solution; however most laboratory practice involves supported electrophoresis, in which the separation is carried out in or on a support material (e.g. paper for paper electrophoresis and various gels for gel electrophoresis). For large nucleic acids, agarose gels are generally used as a support; for smaller nucleic acids or proteins, polyacrylamide gels are more common. Electrophoresis is often carried out under denaturing conditions, with unfolded sample molecules, where separation occurs according to molecular weight. Under native conditions, separation depends on molecular weight, conformation, and particle charges. To make them visible, colourless compounds are dyed with suitable reagents after electrophoresis. For example, ethidium bromide is used for nucleic acids, and coomassie brilliant blue is used for proteins.