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Next: The Partial Digest Problem Up: Biotechnological Methods Previous: Restriction Enzymes

Gel Electrophoresis

Gel electrophoresis is a technique used to separate a mixture of digested DNA fragments. An electrical field is used to move the negatively charged DNA molecules through porous agarose gel. Fragments of the same size and shape move at the same speed, and because smaller molecules travel faster then larger molecules, the mixture is separated into bands, each containing DNA fragments of the same size.

Figure: gel electrophoresis [4]


The amount of exposure the DNA receives to restriction enzymes determines the portion of possible sites that were actually cleaved. Therefore, by applying different exposures to the same DNA sequence, we can measure all possible lengths of DNA fragments, that one can obtain using a particular enzyme. From this information we can attempt to find out where are the sites located in the original molecule. This problem is known as:

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