Final answer:
The gel bands indicate the presence of one restriction cut site in the foreign DNA, which separates the DNA into two pieces.
Step-by-step explanation:
When analyzing gel bands after restriction enzyme digestion, one can determine that there is one restriction enzyme cut site which cuts our foreign DNA into two parts. This is evident when both the foreign DNA and a plasmid are cut with the same restriction enzyme and reveal identical patterns on a gel, indicating that they have similar restriction sites.
This specific site occurs only once within the plasmid, notably in the middle of the lacZ gene, an enzyme necessary for the metabolism of lactose. When the lacZ gene is cut, it prevents the production of the enzyme β-galactosidase. This precise cutting by restriction enzymes creates 'sticky ends' on the DNA fragments, which can attach to another fragment of DNA cut with the same enzyme, facilitating the formation of recombinant DNA.