Regarding DNA preparation, Blake had good results using 1 mL 10^9 PFU High Titer phage preparations.  His DNA had been suspended into 100 uL of water at the end of the phage DNA preparation procedure, and he would use 5 uL of this DNA for restriction digestion.  We will take the same approach.  Each 20 uL "cut" will contain:

2 uL buffer,

1 uL BSA,

1 uL Enzyme,

5 uL DNA.

The digestion will occur at 37°C for 2-3 hours, and will then immediately be loaded onto a gel.  During the 2-3 hour gap, we will run 5 uL of each DNA sample in a different gel to determine whether there is any DNA or not, running the DNA for 5 min at 100 V.  No DNA? The student should have time to prepare new DNA today so that digestions can be done tomorrow with that DNA...the reason for having 2 digestion days.