A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes.

Flexibility in the use of dynamic protein structures is a common theme in bacteria. Tubulin filaments are elementary parts of the cell-division apparatus as well as mediators of plasmid segregation.

Scientists have identified essential genetic code for a method called plasmid curing, which aims to 'displace' antibiotic resistance genes from bacteria.