The term gene splicing refers to molecular biochemical techniques used to attach different DNA molecules to one another. The resulting recombinant DNA can be used for many subsequent purposes. Gene splicing, more commonly referred to as cloning, is a basic technique widely used in genetic, biochemical, and increasingly, physiological studies.

A simple and common splicing method relies on the use of restriction endonucleases to cleave the DNA molecules. The fragment of DNA of interest must then be entered into a vector molecule in order to make many copies of the DNA. The vector, generally a bacterial plasmid, is also cleaved with an enzyme that will leave ends that can be annealed to the fragment ends, usually the same enzyme or combination of enzymes used to cleave the fragment.

Many restriction enzymes leave overhanging single-stranded ends that are complementary to each other on the different DNA molecules...