Dr. Grace Dzido, MD is an internal medicine doctor who practices in Roanoke, VA. She is 54 years old and has been practicing for 19 years.
The Loading Dye * Loading dye is a colored buffer mixed with the DNA prior to loading onto the gel. The loading dye contains a relatively high concentration of either glycerol or sucrose. This makes the solution more dense than the surrounding running buffer so that when a sample is pipetted over top of a well it sinks down into the well.
The figure below shows what happens when dye is placed on top of a layer of gelatin. Over time, the dye mixes with the gelatin. Why does this happen? Everything, including the gelatin and the dye, is made of tiny moving particles. Particles tend to move from places where they are crowded to places where they are less crowded.