What is the purpose of adding a stain before electrophoresis?

Adding a stain before electrophoresis serves primarily to provide visualization of the samples being separated. In the context of gel electrophoresis, dyes are often included in the sample or applied after the process to specifically bind to biomolecules like nucleic acids and proteins. This staining allows for the differentiation of these molecules during and after electrophoresis, making them visible for analysis.

Having a visual marker is essential because it enables researchers to assess the migration patterns of the samples, estimate their sizes based on known standards, and confirm the presence or absence of target molecules. The ability to see the stained bands on the gel directly impacts the interpretation of the results, allowing for better data collection and analysis in various bioscience applications.

While enhancing protein binding, decreasing sample size, or stabilizing protein structure may play roles in certain lab techniques, they do not directly pertain to the main goal of staining before electrophoresis, which is focused solely on visualization.