Loading a gel established the starting line

DNA samples will be run in the electrophoresis box and the gel can be placed in the box with electrophoresis buffer prior to loading the sample wells (Fig. 9). DNA samples are brought to the starting line of the electrophoresis gel with the use of a pipette. The pipette can dispense a measured amount of DNA sample into each sample well. Since the DNA in solution lacks color, a dense tracking dye solution is often mixed in to visualize the gel loading process (Fig. 10). It is easy to see that the gel loading step must be done with care to avoid mixing of samples (Fig. 11). When the DNA solution plus tracking dye are loaded, the well will hold the colored mix in place until all the samples are loaded (Fig. 12). Now it is time for the race to determine which lane has DNA samples with longer fragments and which lane has DNA samples with shorter fragments.

Fig. 9. Placing the gel into the gel box. (Image by D. Lee)

Fig. 10. A tracking dye is mixed with each DNA sample. (Image by D. Lee)

Fig. 11. Using a pipette to load the DNA samples. (Image by D. Lee)

Fig. 12. The tracking dye aids in loading the samples. (Image by D. Lee)