In the following schematic of electrophoretic separation of DNA topoisomers, Band 2 represents

In the following schematic of electrophoretic separation of DNA topoisomers, Band 2 represents Linear DNA. Topoisomers are molecules having similar chemical formula but different topologies. Due to the difference in topologies, these molecules get different resistance while traveling on the gel. This resistance affects their migration on the gel. Therefore, linear DNA move fast as compared to nicked circular DNA but fall behind then supercoiled and circular sinle stranded DNA.