What is the main use of loading dye in electrophoresis?

Loading dye serves a crucial role in the process of electrophoresis, primarily for the purpose of tracking the progress of DNA or proteins during the separation process. When samples are loaded into a gel for electrophoresis, the loading dye is included to provide both density and visibility. The dye ensures that the samples sink properly into the wells of the gel instead of diffusing into the buffer and helps monitor how far the samples have migrated through the gel during the application of an electric current.

As the electrophoresis runs, the migration of the loading dye can be observed, allowing researchers to estimate when to stop the process based on the progress of the samples relative to the dye. This real-time tracking is essential for achieving optimal separation of the biomolecules being analyzed. While loading dye can help visualize streaks created by the dye itself, its primary purpose is to act as a marker for tracking the movement of the samples as they undergo separation.