The cloned set of all DNA fragments from a particular organism is known as its genomic library. Genomic libraries are generated by a procedure known as shotgun cloning. The chromosomal DNA of the organism is isolated, cleaved to frag- ments of cloneable size, and inserted into a cloning vector. The DNA is usu- ally fragmented by partial rather than exhaustive restriction digestion so that the genomic library contains intact representatives of all the organism’s genes, including those that contain restriction sites. DNA in solution can also be me- chanically fragmented (sheared) by rapid stirring.