Heather just recovered a cloned synthetic spider silk gene (DNA
fragment) from a plasmid vector. To excise/release the silk
fragment from the recombinant plasmid, she used a SmaI enzyme
(single restriction digestion of recombinant plasmid DNA). Thanks
to this experiment, knowing the size of the original (empty)
plasmid vector, she determined the silk insert size to be exactly
2000bp long (base pairs; or 2 kbp). To further characterize this
silk insert, she first isolated this 2 kbp silk fragment from the
agarose gel- through a standard electroelution process following
electrophoresis of the SmaI digestion of the recombinant plasmid.
She now decides to construct the complete restriction map of this
linear silk fragment.  

Using the HindIII restriction enzyme, and the EcoRI restriction
enzyme to digest this 2,000 bp silk fragment, she wishes to
determine the number and sizes of the fragments produced by each
enzyme acting alone in a single digestion (using either HindIII,
OR, using EcoRI), or acting in combination in a double restriction
digestion (both enzymes used simultaneously, HindII/EcoRI digest).
Heather obtained the results for each type of single, or double
restriction digestions she performed by analyzing the different
digestion samples through agarose gel electrophoresis. She recorded
the data from the different restriction digestions’ electrophoretic
profiles in the table below.

She also drew a cartoon representing the different
electrophoretic profiles for all restriction digestions
performed.

AFTER explaining to Heather what these ‘bands’ in the ethidium
bromide stained agarose gel- visualized under UV light -represent,
please help her construct the linear restriction map of her 2,000
bp silk insert i.e. determine the number AND positions of ALL
HindIII and EcoRI restriction sites in this linear insert. She
needs this information in order to clone this fragment into a
bacterial expression vector that will allow for the recombinant
production of silk proteins that she needs to spin into synthetic
fibers.