Gel electrophoresis

Gel electrophoresis is a method to separate different kinds of molecules in a mixture by letting them pass through a gel?, driven by an electric current. The gel is placed in a tank with ionic buffer?, and the mixture to separate is injected into the gel near the cathode. When the electric current is applied, the (negatively charged) molecules travel towards the (positive) anode. The smaller and the more negatively charged the molecules are, the faster they pass through the gel.

After the electrophoresis run, when the smallest molecules have almost reached the anode, the molecules in the gel can be stained? to make them visible. If several mixtures have initially been injected next to each other, they will run parallel in individual lanes. Depending on the number of different molecules, each lane shows more or less distinct bands. Bands in different lanes that end up at the same "height" contain molecules that passed through the gel with the same speed, which usually means they are about the same size. There are special markers available, which contain molecules of known sizes. If such a marker was run on one lane in the gel parallel to the mixture(s), the bands it displays can be compared to those of the mixture(s) in order to determine their size.

Gel electrophoresis is used in genetics and biochemistry:

• Gel elctrophoresis of DNA or RNA is usually done by agarose gel electrophoresis.
• Gel electrophoresis of proteins is usually done in an SDS? gel (SDS-PAGE?), or by [native gel electrophoresis]?.

See also : agarose gel electrophoresis -- SDS-PAGE?

Back to : genetics -- biochemistry -- molecular biology