Gel Electrophoresis: The Key Technique for Separating Charged Molecules

Gel Electrophoresis: A Powerful Technique for Molecular Separation

Gel electrophoresis is a widely used technique in molecular biology and biochemistry for separating charged molecules, such as DNA, RNA, and proteins, based on their migration through a gel matrix when subjected to an electric field. The correct answer to the question is:

✅ B. Gel Electrophoresis

This technique is essential for analyzing genetic material, protein expression, and molecular interactions.

Principle of Gel Electrophoresis

Gel electrophoresis works by applying an electric current to a gel, which creates an electric field. Molecules move through the gel at different rates depending on their size and charge. Negatively charged molecules, like DNA and RNA, migrate toward the positive electrode (anode), while proteins may require SDS (sodium dodecyl sulfate) treatment to impart a uniform negative charge.

Steps in Gel Electrophoresis

1. Preparation of the Gel

   • Agarose gel is used for DNA and RNA separation.
   • Polyacrylamide gel is used for proteins and small nucleic acids.

2. Loading the Sample

   • DNA or proteins are mixed with a loading dye and placed into wells in the gel.

3. Application of Electric Field

   • The gel is submerged in a buffer solution, and an electric current is applied.

4. Molecular Separation

   • Smaller molecules travel faster and farther, while larger molecules migrate slower.

5. Visualization

   • DNA is stained with ethidium bromide or SYBR Green and viewed under UV light.
   • Proteins are stained with Coomassie Blue or Silver Stain.

Why Are the Other Options Incorrect?

❌ A. Photoreactivation – A DNA repair mechanism, not a separation technique.

❌ C. Autoradiography – A detection method for radioactively labeled molecules.

❌ D. Eastern Blotting – Used for studying protein modifications, not for molecular separation.

Conclusion

Gel electrophoresis is a fundamental technique for biological and forensic research, allowing scientists to analyze genetic material, identify mutations, and study proteins.