Practice question

Sodium dodecyl sulfate polyacrylamide gel electrophoresis provides indispensable size-based separation before Western blotting. SDS is an anionic detergent binding at approximately 1.4 grams per gram of protein, masking intrinsic charge and unfolding polypeptides into rod-like structures. Inclusion of reducing agents like dithiothreitol cleaves disulfide bridges. Migration through polyacrylamide sieving matrix then depends solely on polypeptide length logarithmically. This allows precise molecular weight estimation and resolution of isoforms. Techniques such as RT-PCR amplify nucleic acids, electroporation introduces DNA into cells, and ELISA detects without size resolution, none replicate SDS-PAGE function.