I am having trouble understanding what is the source of band "2" in the following gel-electrophoresis:
In this experiment, we took an E.coli transformant colony and ran its nucleic acids in the gel, after adding a restriction enzyme which cuts the recombinant plasmid molecule into two corresponding bands ("3" and "5" ["5" is very weak in the scanned version, but is well seen in the "hard copy" ) . I know the first line ("1") corresponds to possible genomic DNA we took from untransformed bacteria, and that the fourth line ("4") corresponds to a plasmid molecule without an insert. 6 is also well understood.
My question is- What is the source of band "2" which contains more base pairs than any of the parts of the plasmid and its insert , and in particular more base pairs than the insert?
WIll someone please help me understand this ?
Thanks in advance