During electrophoresis, crescent-shaped bands develop. The next course of action is to repeat the electrophoresis and which of the following?

During electrophoresis, crescent-shaped bands develop. The next course of action is to repeat the electrophoresis and which of the following?

• A. Repeat electrophoresis and do not overload the sample
• B. Overload the sample
• C. Extend run time
• D. Increase voltage

Answer: (A)

Crescent-shaped bands signal that too much sample was loaded, causing distortion as the gel matrix and buffer can’t separate the molecules cleanly. The fix is to repeat the electrophoresis but with less sample (or a more diluted sample) so the bands become well defined and evenly shaped. Simply extending the run time or increasing voltage tends to worsen artifacts like band distortion or overheating, and loading more sample would exacerbate the problem rather than solve it.

Crescent-shaped bands signal that too much sample was loaded, causing distortion as the gel matrix and buffer can’t separate the molecules cleanly. The fix is to repeat the electrophoresis but with less sample (or a more diluted sample) so the bands become well defined and evenly shaped. Simply extending the run time or increasing voltage tends to worsen artifacts like band distortion or overheating, and loading more sample would exacerbate the problem rather than solve it.