Gel Electrophoresis
When DNA is treated with restriction enzymes, the DNA is cut into fragments of various sizes. These fragments can be separated in a gel on the bases on their electric charge and size.
1. DNA is cut up with restriction enzymes.
2. The DNA fragments are transferred to wells cut into a gel.
3.An electric charge is transferred through the gel. The negatively charged DNA fragments are repelled by the negative electrode and attracted to the positive electrode.
The animation below shows the separation of three different samples of DNA. The samples are run at the same time, in the same gel.
The resulting pattern is known as a DNA fingerprint. If identical patterns appear in different column the samples may be from the same source.