The principle of electrophoresis states that in the presence of an electric field, a charged particle moves toward the region of an opposite charge. When the particle has unequal charge distribution in its chemical bonds, it aligns on the electric potential.
An electrode is any conducting material that creates an electrical field to allow current to pass through. The positive end of an electrode is called an anode while the negative end is called a cathode. When a negatively charged particle travels along an electric field, it tends to migrate toward the anode and move against frictional force. The bigger the particle, the slower it moves.
In the fields of molecular biology and biochemistry, electrophoresis is a useful analytical technique where macromolecules of varying sizes and densities are separated. Complex proteins and nucleic acids that undergo electrophoresis move through a gel matrix that is primarily composed of polymerized agarose or polyacrylamide. Agarose is a polysaccharide that forms a gelatin-like substance when dissolved in boiling water. Polyacrylamide is a type of solid gel created by polymerization of acrylamide solutions through the addition of ammonium persulfate coupled with tetramethylenediamine.
Agarose gel is mainly used for separating complex protein molecules and DNA or RNA fragments. Larger molecules get trapped against the porous material while smaller particles pass through easily. Modern researchers prefer the use of polyacrylamide gel. Other forms of gel electrophoresis include isoelectric focusing, 2D electrophoresis, capillary electrophoresis and western blotting.