And notice this DNA probe will not form the same double helix with any of these other bands because the other bands don't have that complementary sequence. So this molecule is a single stranded DNA fragment of interest that we want to actually detect. And the green molecule is that radioactively labeled DNA probe that contains a nucleotide sequence that is complementary to that restriction fragment above that we essentially want to detect. And once we carry out step three, then we can use the process of order radiography and that will allow us to pinpoint exactly where that fragment is. And now we know if we go back to this setup, that this band C contains those fragments that we want to isolate. And so we can take out the fragments, remove the other unwanted fragments, and now we have a pure solution that contains only the fragment, only that gene that we were actually interested in the first place.