Question

Assume that you have cut λ dna with the restriction enzyme hindiii. you separate the fragments on an agarose gel and stain the dna with ethidium bromide. you notice that the intensity of the stain is less in the bands that have migrated closer to the "+" pole. give an explanation for this finding.

Answer 1

The smaller fragments bind less stain than larger fragments that are near the origin. This is because the smaller fragments migrate toward the "+" pole. The ethidium bromide is a stain that makes the bands to fluoresce when they are excited with the ultraviolet light.