Question

A mixture of fragmented DNA was electrophoresed in an agarose gel. After staining the gel with ethidium bromide, no DNA bands were observed. What could be the reason?

Answer 1

A mixture of fragmented DNA was electrophoresed in an agarose gel. After staining the gel with ethidium bromide, no DNA bands were observed. This could happen due to one or all of the following reasons:

1. The mixture got contaminated with nucleases.

2. The concentration of the gel was not proper.

3. The anode and cathode were put in opposite orientation.

4. The concentration of EtBr was not enough to be intercalated within the bases of the DNA.