There is often a need to identify specific fragments of DNA that have been separated by electrophoresis. This can effectively be done by Southern blot hybridization. The DNA fragments within an electrophoresis gel are transferred onto a filter such as nitrocellulose and immobilized. Then the specific fragments of DNA are hybridized, or attached, to a complementary radiolabeled probe. The location of the homologous bands of DNA can then be identified...