Many enzymes break down polymers to monomers to aid in digestion of food. Restriction endonucleases are different. What is different and important about Restriction endonucleases?
Restriction endonucleases are enzymes which digest DNA. They are not like digestive enzymes which completely digest DNA to monomers so cells can eat nucleic acids. A "restriction endonuclease" is an enzyme that digest/cuts DNA in a specific place but leaves most of the DNA molecule unchanged.