Electrophoresis is a chemical phenomenon in which an electric charge in a solution moves toward an electrode of opposite charge under an electric field between electrodes.
Electrophoresis was devised by Swedish biophysicist Arne Tisselius during the study of blood proteins in the 1930s. Arne Tissellius was awarded the Nobel Prize in Chemistry in 1948 for his contribution to the design of an electrophoretic method.
Generally, DNA is electrically (-) polar, and when placed in an electric field, it moves toward (+) polarity. Using this property, fragmented DNA can be classified according to its length.
Briefly, the experiment method is as follows.
- DNA is extracted from the collected cells.
- The DNA is treated with restriction enzymes and divided into small pieces.
- If necessary, stain the DNA sample ("loading dye" - observable by the eye).
- Place the DNA sample on the electrophoretic plate and connect the electrodes.
- When electrophoresis is complete, treat it with a fluorescent dye and then illuminate it with ultraviolet(UV) light.
The electrophoretic plate is made from agarose gel extracted from seaweed. The agarose gel is a net structure in which the threads are intertwined, so the larger the size of the solute passing through, the slower the gel passes. That is, the shorter the length of the DNA, the more it is detected in the near position of the (+) electrode.
There are two types of staining for observing DNA fragments: loading dye and fluorescence dye (UV dye).
Of these, "loading dye" is for observing progress. For detailed observation, fluorescence staining should be added after electrophoresis. When the UV lamp is illuminated, the fluorescent material converts the ultraviolet light into visible light, which makes it easy to observe with the eyes.