What is the primary function of a cathode in electrophoresis?

The primary function of a cathode in electrophoresis is to act as an electrode that has a negative charge. During electrophoresis, a voltage is applied across a gel or other medium containing charged molecules, such as proteins or nucleic acids. The cathode, being negatively charged, attracts positively charged particles (cations) towards it, allowing for the separation of molecules based on their charge and size. This process is essential for analyzing biomolecules, as it allows for their resolution and identification within a mixture.

In the context of electrophoresis, the anode, which is positively charged, attracts negatively charged particles (anions), and together, they facilitate the movement of charged molecules through the gel matrix. The negative charge of the cathode is crucial because it drives the migration of positively charged species toward it, effectively enabling the experiment's purpose.

Understanding the role of the cathode helps students grasp the fundamental mechanics of electrophoretic techniques used in various applications, such as DNA analysis and protein purification.