What is the principle behind the Western Blot?

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What is the principle behind the Western Blot?

The essential idea behind a Western blot is separating proteins by size using gel-based electrophoresis, then transferring them to a membrane and detecting a specific protein with antibodies. In practice, proteins are treated with a detergent like SDS to give them a uniform negative charge and to unfold them, so their movement through a polyacrylamide gel under an electric field depends mainly on molecular weight—smaller proteins travel farther than larger ones. After this size-based separation, the proteins are blotted onto a membrane and exposed to an antibody that binds the protein of interest; a labeled secondary antibody reveals that binding, showing whether the target protein is present and, often, roughly how much. This combination of separating by size and then using antibody-based detection is what makes the Western blot unique. Other options don’t fit because centrifugation separates by density rather than size in a gel, liquid chromatography relies on different interactions for separation, and sequencing targets nucleic acids rather than proteins.

The essential idea behind a Western blot is separating proteins by size using gel-based electrophoresis, then transferring them to a membrane and detecting a specific protein with antibodies. In practice, proteins are treated with a detergent like SDS to give them a uniform negative charge and to unfold them, so their movement through a polyacrylamide gel under an electric field depends mainly on molecular weight—smaller proteins travel farther than larger ones. After this size-based separation, the proteins are blotted onto a membrane and exposed to an antibody that binds the protein of interest; a labeled secondary antibody reveals that binding, showing whether the target protein is present and, often, roughly how much. This combination of separating by size and then using antibody-based detection is what makes the Western blot unique.

Other options don’t fit because centrifugation separates by density rather than size in a gel, liquid chromatography relies on different interactions for separation, and sequencing targets nucleic acids rather than proteins.

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