Agarose Gel Electrophoresis - How to prove two bands are same size? - (Nov/28/2009 )

from a gel electrophoresis photo of plasmids, how might you prove that two bands of same size in two profiles represent the same plasmid?

thank you in advance

From photos? You can't prove they're the same plasmid -- the best you can say is that the bands are approximately the same size...

You'd need to do much more work to prove the bands are the same plasmid....

You cant prove it per se using that method. However, if you know what the plasmids are supposed to look like, you can do an extensive enzyme digestion assay and compare the fragments. If all the fragments from both plasmids are approximately the same size, you can argue that they are probably from the same plasmid.

thank you all