How gel electrophoresis works

1. DNA fragments are pipetted into the wells at the top of the gel furthest from the anode;
2. Dense loading buffer mixed with DNA sample to help it sink to the bottom of the well
3. Loading dyes added to allow visualization of separation process
4. Negatively charged DNA migrates out of well, toward anode when subjected to an electric field
5. Fragments migrate through an agarose gel matrix made out of a meshwork of polysaccharides, which impedes movement of longer fragments more than shorter fragments.
6. Longer fragments migrate slower compared to shorter fragments.