Casting of the agarose gel- Different steps to cast the agarose gel for horizontal gel electrophoresis are given in Figure 24.2. The agarose powder is dissolved in a buffer (TAE or TBE) and heated to melt the agarose. Hot agarose is poured into the gel cassette and allowed it to set. A comb can be inserted into the hot agarose to cast the well for loading the sample. In few cases, we can add ethidium bromide within the gel so that it stains the DNA while electrophoresis.

Figure 24.2: Different steps in casting of the agarose gel for horizontal gel electrophoresis apparatus.

Running and staining- The gel cassette is placed in the electrophoresis tank submerged completely and DNA loaded into the well with the help of pipetman and run with a constant voltage. DNA runs from negative to positive end and ethidium bromide (EtBr) present in the gel stain the DNA. Observing the agarose gel in a UV-chamber shows the DNA stained with EtBr as organe colored fluorescence (Figure 36.3).