Gel electrophoresis is a technique used in recombinant DNA technology for the separation of fragments of DNA on the basis of their size. In this method the DNA fragments are run in an electric field and because the fragments have the same charge by mass ratio the separation is only on the basis of the size of the fragments, with the smaller fragments moving faster (with the bands being seen lower in the gel) and the larger fragments slower (with the bands being seen at the top). In recombinant DNA technology, the isolated DNA fragments can be separated and analysed by this technique.