After electrophoresis, the different fragments are visualized as bands at specific distances from the top of the gel (the negative electrode end) on the basis of their size. The sizes of the nucleic acid samples can be estimated by comparing the distance with the molecular weight standard samples (also calledDNA ladder).
每个片段将是一个乐队的凝胶。一个混合物of fragments of varying sizes appears as a long smear. If the fragments are too large, e.g. uncut genomic DNA, they will form a single large band at the top of the gel.
Figure 1:A completed gel electrophoresis experiment with 5 samples and the DNA ladder on the right. The DNA ladder can be used to estimate the sizes of the bands in the samples.
Circularplasmidsmove at different speeds depending on their conformation (nicked, linear, covalently bound, supercoiled, and circular single stranded). A supercoiled plasmid travels faster because it has less friction against agarose matrix than nicked or linear plasmid.
If you want to isolate a specific fragment you can cut the gel andextract the DNA.