7 ul of DNA was extracted and added to 63 ul of TE. After mixing
those two amounts together, you used a spectrophotometer to measure
the A260 of your sample. Suppose that your reading was A260 = 0.3.
You still have 93 ul of DNA extract sitting in your original sample
tube.

a) What mass of DNA (in µg) is now sitting in that original
tube?

b) If you now want to set up a single restriction digest with
0.5 µg of fish DNA in it, what volume do you take from your
original sample tube?

c) What else do you add to the tube to set up a restriction
digestion of that sample, and in what volume? Let’s say you are
using the restriction enzyme HindIII with a concentration of 5
U/µl, you want a 2-fold “excess” of enzyme for a 1 hour digest, and
you want your restriction digest to have a final volume of 25 µl).
Fortunately, the manufacturer shipped a tube of 10X HindIII buffer
with your enzyme.