What is the significance of running an uncut plasmid on electrophoresis gel?
It is used to determine whether the unused/excess amount of plasmid has contaminated the  final solution of the desired recombinant DNA  or not.
Electrophoresis is performed on the &quot;Blank&quot;(uncut) plasmid to define its bands.If the electrophoresis result contains the bands of both &quot;blank&quot; and recombinant DNA , it shows that your solution is not 100% pure.