Plasmid

A DNA molecule that replicates independently of a cell’s chromosomes. Plasmids are common in bacteria and can carry genes between cells.

Origin of replication: A DNA sequence where replication begins. Plasmid replication starts at this sequence, which helps determine copy number and host range.
Bacterial chromosome: The main DNA molecule carrying a bacterium’s essential genetic information. Plasmids replicate separately from this principal genetic molecule.
Cloning vector: A DNA molecule engineered to carry and replicate inserted DNA in a host cell. Plasmids are widely used as vectors for copying specific DNA sequences.
Antibiotic resistance: The ability of microorganisms to survive exposure to drugs that would normally inhibit or kill them. Plasmids can carry resistance genes and spread them among bacteria.
F plasmid: A bacterial plasmid that enables conjugation in Escherichia coli and related bacteria. It is a classic example of a plasmid that promotes cell-to-cell DNA transfer.
Plasmid partition system: A molecular system that distributes replicated plasmids to daughter cells during cell division. Partition systems help ensure plasmids reach both daughter cells when a cell divides.
Circular DNA: DNA whose two ends are joined to form a continuous loop. Many bacterial plasmids are circular, though linear plasmids also exist.
Expression vector: A DNA construct designed to produce RNA or protein from an inserted gene. Engineered plasmids can drive production of a chosen protein in host cells.
R plasmid: A plasmid carrying one or more genes that confer resistance to antimicrobial drugs. These plasmids can combine resistance traits and transfer them between bacterial strains.
Col plasmid: A plasmid carrying genes for bacteriocins, proteins that inhibit or kill related bacteria. It illustrates how plasmids can give bacteria an advantage over competitors.

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