Which medium is used for charge-based separation in electrophoresis?

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

Answer: (A)

In electrophoresis, molecules move toward the electrode of opposite charge, and the gel medium provides a sieve that shapes how fast they travel. Agarose forms a relatively loose, uniform network with larger pores, which works well for large biomolecules like DNA and RNA. Since these nucleic acids carry a consistent negative charge, their overall speed is mainly determined by how easily they can pass through the gel pores. That makes agarose an excellent medium for achieving charge-driven separation of nucleic acids, effectively resolving fragments by size while the electric field provides the driving force. Other media serve different focuses—cellulose acetate is commonly used for protein separation by charge, while polyacrylamide gels offer higher resolution for smaller molecules and proteins—but for general charge-based separation of nucleic acids, agarose is the standard choice.