In your laboratory you will be given three samples of DNA obtained from a virus, the bacteriophage lambda. One sample will be uncut DNA, one will be incubated with the restriction enzyme HindIII, and one will be incubated with EcoRI. You will separate the fragments of DNA by electrophoresis, stain the DNA for visualization, and determine the fragment sizes formed in the EcoRI digest.

The figure below is an overview of the procedure, using generalized DNA samples. Over the following several pages we look at the procedure step by step.