Gel analysis of fragments in step 6 shows that even though the undigested DNA and DNA digested with HindIII are both 1000 bp, they do not run exactly the same distance on a gel. Explain one possible reason for this discrepancy.

Size of the band varied

Explanation:

In the given question, the options are not provided but based on the information provided in the question, it can be predicted.

When the DNA was digested by the HindIII, then the length of the digest came about 1000 bp and the undigested DNA was also found 1000 bp.

When both the bands were analysed by Gel electrophoresis then the bands do not run to the same distance therefore this shows that the size of both the bands was not equal and their size varied.

Thus, the size of the band varied is correct.