Bacterial artificial chromosome

A Bacterial Artificial Chromosome (or BAC) is a DNA construct, based on a fertility plasmid, used for transforming and cloning in bacteria, usually E. coli. Its usual insert size is 150 kbp, with a range from 100 to 300 kbp.

BACs are often used in sequencing other organisms, in genome projects, for example the Human Genome Project. A short piece of the organisms DNA is amplified as an insert in BACs, then sequenced. Finally, the sequenced parts are rearranged in silico, resulting in the genome sequence of the sequenced organism.