in gel electrophoresis, a loading dye is usually added to the sample of dna to be loaded in the wells of the gel. why would this be important?

Gel loading dye is typically made at 6X concentration (0.25% bromphenol blue, 0.25% xylene cyanol, 30% glycerol). Loading dye helps to track how far your DNA sample has traveled, and also allows the sample to sink into the gel. ... It is important to use the same running buffer as the one used to prepare the gel.