Final answer:
In SDS-PAGE, proteins are separated based on size after being denatured by SDS, which imparts a uniform negative charge to all proteins, thereby nullifying the influence of intrinsic protein charges on migration during electrophoresis. The gel's pore size determines the separation efficiency, and stained bands allow for visualization of the separated proteins.
Step-by-step explanation:
In SDS polyacrylamide gel electrophoresis (SDS-PAGE), proteins are separated based on their size. The process involves denaturing the proteins using a detergent known as sodium dodecyl sulfate (SDS), which coats proteins with a uniform negative charge, thereby masking their native charges. This allows the separation to occur based solely on molecular size, since the uniform charge-to-mass ratio eliminates the effect of the protein's intrinsic charge on its migration speed during electrophoresis.
The separation happens within a gel matrix made of polyacrylamide, the pore size of which is determined by the ratio of acrylamide to methylenebisacrylamide. Smaller proteins will migrate through the gel faster than larger ones when an electric voltage is applied. After the electrophoresis, proteins can be visualized within the gel typically using staining agents like Coomassie blue or silver stain.