The abbreviation for the bacterial artificial chromosomes is known as BACs. It involves a DNA construct based on the bacterial plasmids. The bacteria possess fertility plasmid known as the F-plasmid. It helps in the process of conjugation or a unidirectional gene transfer. Genetic engineers use F-plasmid for transformation and cloning experiments. Their insert size involves 100-350 kbp. The F-plasmid consists of partition genes. These genes promote even distribution of the plasmids. Human Genome Project highly utilized BACs. They involve high accuracy and stability. They show an ability to replace the whole genome shotgun approach. These chromosomes become easy to handle. The bacterial cells undergo a process of conjugation involving the transfer of the F-plasmid from the donor to the recipient cell. Construction of the BACs requires F-plasmid like a raw material. BACs get purified as plasmid DNA. The components of BACs include the origin of replication, par A and par B components, antibiotic resistance genes, and the phage promoters. The origin of replication or the oriS (also known as rep E-F) plays a crucial role in initiating the replication. It regulates the copy number of the plasmids. The maintenance of BACs requires components such as the parA and parB. These components help in stabilizing the bacterial artificial chromosomes. They play an important role in the cell division process and help in the formation of daughter cells. The antibiotic gene help in identifying the recombinants. They act as selectable markers. The phage promoters also serve in constructing used the BACs. Examples include T1 and Sp6 promoters. They help in studying diseases.