hey are of relatively small size (approximately 12kb) and of circular formwhen they areamplifiedor manipulated inE. coli,but are rendered linear and of very large size, i.e. several hundreds of kilobases (kb), when introduced as cloning vectors in yeast. The latter process involves cleavage at strategicallylocated sites by two restriction enzymes, which breakthemintwolinearDNAarms.T