Electrophoresis is a technique used to separate and analyze proteins and other biomolecules based on their size, shape, and charge. In the context of identifying proteins present in a biological sample and determining their molecular weight, the most commonly used method is Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis SDS-PAGE .Here's how electrophoresis, specifically SDS-PAGE, can be used for this purpose:1. Sample preparation: The biological sample containing proteins is mixed with a denaturing buffer containing SDS an anionic detergent and a reducing agent such as -mercaptoethanol or dithiothreitol . This mixture is then heated to denature the proteins, which helps to unfold them and break any disulfide bonds. The SDS binds to the proteins, giving them a uniform negative charge proportional to their size.2. Gel preparation: A polyacrylamide gel is prepared with a specific concentration, which determines the pore size of the gel matrix. This gel consists of two parts: a stacking gel with larger pores and a resolving gel with smaller pores. The stacking gel helps to concentrate the proteins into a single band, while the resolving gel separates the proteins based on their size.3. Loading and running the gel: The prepared protein samples are loaded into wells at the top of the gel. An electric field is applied across the gel, causing the negatively charged proteins to migrate towards the positive electrode anode at the bottom of the gel. The smaller proteins move faster through the gel matrix, while the larger proteins move slower, resulting in the separation of proteins based on their molecular weight.4. Staining and visualization: After electrophoresis, the gel is stained with a protein-specific dye, such as Coomassie Brilliant Blue or silver stain, which binds to the proteins and allows them to be visualized as distinct bands. The intensity of the bands is proportional to the amount of protein present.5. Molecular weight determination: A molecular weight marker also known as a protein ladder containing proteins of known molecular weights is run alongside the samples. By comparing the migration distance of the sample proteins to that of the marker proteins, the molecular weight of the proteins in the sample can be estimated.In summary, electrophoresis, specifically SDS-PAGE, can be used to identify the proteins present in a biological sample and determine their molecular weight by separating them based on their size and charge, visualizing the separated proteins as distinct bands, and comparing their migration distance to a molecular weight marker.