How do you create a simple linear stretch of DNA that goes on and on, like some kind of endlessly meandering oil pipeline?
Well, first of all, you beat the living hell out of it so it breaks up into fragments. Next, get rid of any nonlinear fragments because, face it, they can’t be sequenced anyway. This is most easily done by throwing out the phenol phase used for DNA extraction which may contain any troublesome DNA/protein/lipid etc interactions. Next, take what’s left (linear DNA fragments) and artificially splice them together in your mind using overlapping sequences. If this doesn’t always work, just extrapolate until it does. Voilà! We now have a nice, neat (if somewhat boring) endlessly linear, stretch of DNA.