In some experiments you will perform a PCR.
Two primers are available for PCR:  Bam+ and Eco- primers:

PCR produces a large amount of DNA containing the sequence of the primers and the region between them.

Some groups will not cut out the fragment for labelling from gel, but will do a PCR to amplify the fragment from a premade Lambda clone, i.e. one of these.

Others will do a colony PCR on transformants to find clones with the HindIII deletion.