Restriction and modification enzymes serve as nature’s genetic gatekeepers. These specialized proteins function together as a defence mechanism in bacteria and protect them from invading foreign DNA, such as that of bacteriophages. Restriction enzymes, also known as restriction endonucleases, recognize specific sequences within the DNA and cleave it at or near these sites. This precise cut enables scientists to isolate genes, manipulate genetic material, and create recombinant DNA. On the other hand, modification enzymes, primarily DNA methyltransferases, act as protectors for the host DNA by chemically modifying it, typically through methylation at specific bases. This modification prevents restriction enzymes from cutting the host DNA, ensuring a seamless balance between self-defence and normal cellular function. Restriction and modification enzymes are applied in cloning, DNA mapping, and genome editing technologies like CRISPR. ....