Electrophoresis:

Electrophoresis is a method which is used to separate and purify macromolecules especially proteins and nucleic acids which differ in size, charge or conformation.  Electrophoresis is motion of dispersed particles relative to the fluid under the influence of a spatially uniform electric field. It is caused by the presence of a charged interface between the particle surface and surrounding fluid. The dispersed particles have an electric surface charge, on which the external electric field exerts an electrostatic Coulomb force. The electric field produces a force on the ions in the diffuse layer which has direction opposite to that acting on the surface charge. The force produced by electric field is to the ions in the diffuse layer located at some distance from particle surface, and part of it is transferred to the particle surface through viscous stress. This part of the force is called as electrophoretic retardation force. The molecular dynamics states that a surface charge is not always required for electrophoresis to take place, and that even neutral particles can migrate in an electric field because of the molecular structure of water at the interface. Gel electrophoresis is a technique used for the separation of DNA, RNA, or protein molecules by using an electric field applied to the gel matrix. DNA Gel electrophoresis is performed usually for analytical purposes and can be used as a preparative technique prior to use of other methods such as mass spectrometry, RFLP, PCR, cloning, DNA sequencing, or Southern blotting for the further characterization. Gel electrophoresis is used in forensics, genetics, microbiology, molecular biology, and biochemistry. The results can be analyzed quantitatively by visualizing gel with the UV light and a gel imaging device. The image is recorded with a computer operated camera, and the intensity of the band or spot of interest is measured and compared against standard or markers loaded on same gel.