Practice question

Loading dyes require a dense component to ensure samples settle at the bottom of wells immersed in running buffer. Glycerol at 5 to 10 percent (v/v) increases specific gravity and viscosity without adding charge, so it does not alter electric field migration. It is chemically inert, transparent, and inexpensive. Sucrose and Ficoll perform similar functions as alternatives. Glycerol does not stain DNA, nor affect conductivity or voltage significantly; its role is strictly physical, preventing sample dispersal and ensuring sharp, well-defined entry into the gel matrix during loading.