Which medium is used for separation by both size and charge in electrophoresis?

• A. Agarose
• B. Cellulose acetate
• C. PAGE
• D. Polyacrylamide

Answer: (C)

Polyacrylamide gel electrophoresis lets molecules be separated by both size and charge because the gel has a fine, controllable pore structure and interactions that influence how fast a molecule moves. In native PAGE, proteins keep their natural charge and conformation, so their migration depends on a combination of their size and their net charge; smaller molecules and/or more highly charged ones travel differently from larger or less charged ones. The gel’s adjustable mesh provides high resolution across a range of sizes, enabling discrimination based on both properties at once. By contrast, agarose gels have larger pore sizes and mainly separate larger biomolecules by size, while cellulose acetate separates largely by charge interactions with the support. So the medium best suited for separation by both size and charge is polyacrylamide gel electrophoresis.