Gel Electrophoresis
Gel Electrophoresis
Last Updated on Wednesday, 11 May 2011 05:43 Written by Administrator Sunday, 27 June 2010 08:36
Gel electrophoresis is the separation of nucleic acids such as DNA and RNA, or proteins through a matrix using an electric current.
Electrophoresis can be conducted for analytical purposes, but also is used as a preparative technique to partially purify molecules.
Separation Method
"Gel", refers to the matrix used to separate the molecules. In most cases the gel is a crosslinked polymer whose composition and porosity is chosen based on the weight and composition of the target of the analysis. When separating proteins or small nucleic acids (DNA, RNA, or oligonucleotides) the gel is usually made with different concentrations of acrylamide and a cross-linker, producing different sized mesh networks of polyacrylamide. When separating larger nucleic acids (greater than a few hundred bases), the preferred matrix is purified agarose (a component of agar which is a red seaweed extract). In both cases, the gel forms a solid but porous matrix that looks and feels like clear Jell-O. Acrylamide, in contrast to polyacrylamide, is a neurotoxin and needs to be handled using Good Laboratory Practices (GLP) to avoid poisoning.
"Electrophoresis", refers to the electromotive force (EMF) that is used to push or pull the molecules through the gel matrix; by placing the molecules in wells in the gel and applying an electric current, the molecules will move through the matrix at different rates, towards the anode if negatively charged or towards the cathode if positively charged (note that gel electrophoresis operates as an electrolytic cell; the anode is positive and the cathode is negative).
