Preparing a gel

The first step in gel preparation is to weigh out the appropriate amount of agarose (Fig. 2). This amount depends on the size of the gel and the size of the DNA segments being separated. Smaller segments will require separation with a more dense electrophoresis gel. The agarose is poured into the water solution with the electrolyte (Figs. 3,4). Usually the electrolyte solution such as Tris borate EDTA is made as a concentrated stock and them diluted for each gel. The agarose and electrolyte solution is then heated and stirred. This works well using a stirring hot plate found in most molecular genetics labs. One can also heat the gel solution in a microwave. As the mixture heats, the agarose goes into solution, forming a clear liquid. Now the gel is ready to be poured.