A
bacterial artificial chromosome (BAC) is a
DNA construct, based on a functional fertility
plasmid (or
F-plasmid), used for
transforming and
cloning in
bacteria, usually
E. coli. F-plasmids play a crucial role because they contain partition genes that promote the even distribution of plasmids after bacterial cell division. The bacterial artificial chromosome's usual insert size is 150-350
kbp. A similar
cloning vector called a
PAC has also been produced from the bacterial P1-plasmid.