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MBBS QUESTION #10307
Question 1
At its isoelectric point (pI), an amino acid or protein:
  • Carries a net positive charge and migrates toward the cathode during electrophoresis
  • Carries a net negative charge and migrates toward the anode during electrophoresis
  • Carries no net charge overall and does not migrate in an electric field✔️
  • Is necessarily fully denatured
Correct Answer Explanation
At the isoelectric point, the number of positive and negative charges on the molecule are equal, giving it zero net charge; consequently it does not migrate toward either electrode during electrophoresis — the principle exploited in isoelectric focusing to separate proteins by pI.