Final answer:
The three main ingredients of gel loading buffer for agarose gel electrophoresis are typically urea, TBE buffer solution, and bromophenol blue dye.
Step-by-step explanation:
The three main ingredients of gel loading buffer used in gel electrophoresis are typically a tracking dye, a density agent, and a buffer solution to maintain pH. In the context provided, the gel loading dye includes a mixture with urea, which serves as a denaturant to keep the DNA strands separate, Tris-borate-EDTA (TBE) as the buffer solution to maintain the pH level, and bromophenol blue, a tracking dye that helps in visualizing the migration of samples during electrophoresis. These are mixed to create the appropriate gel loading buffer that complements the agarose gel electrophoresis procedure for analyzing DNA samples.