A bacterial artificial chromosome (BAC) ia a vector with a large cloning capacity (up to 300 kb).

A BAC is constructed from a fertility plasmid (F factor) that enables conjugation.

A chloramphenicol resistance gene serves to screen for recombinants, while a polylinker contains several restriction enzyme recognition sites for inserting foreign DNA.

Promoter regions at T7 and Sp6 allow expression of inserted genes.