During gel electrophoresis, what is a consequence of overloading the gel with too much sample?

During gel electrophoresis, what is a consequence of overloading the gel with too much sample?

• A. It can cause a smear and poor resolution.
• B. It will improve resolution.
• C. It will automatically digest the DNA.
• D. It changes pH of buffer.

Answer: (A)

Overloading the gel introduces more sample than the matrix can resolve, so the separation by size becomes distorted. The gel’s pores separate fragments as they migrate, but when a lane carries too much DNA (and the associated dye and solvent), diffusion increases and bands broaden, creating a smear. That smear lowers resolution, making it hard to distinguish fragments that are close in size. The buffer’s pH is set by the solution, not by how much sample you load, and loading more sample does not digest DNA or sharpen the bands; it often makes the pattern noisier or spill over into neighboring lanes.

Overloading the gel introduces more sample than the matrix can resolve, so the separation by size becomes distorted. The gel’s pores separate fragments as they migrate, but when a lane carries too much DNA (and the associated dye and solvent), diffusion increases and bands broaden, creating a smear. That smear lowers resolution, making it hard to distinguish fragments that are close in size. The buffer’s pH is set by the solution, not by how much sample you load, and loading more sample does not digest DNA or sharpen the bands; it often makes the pattern noisier or spill over into neighboring lanes.