||This article needs additional citations for verification. (January 2009)
Circular DNA is a form of DNA that is found in viruses, bacteria and archaea as well as in eukaryotic cells in the form of either mitochondrial DNA or plastid DNA.
While the individual strands of a linear double helix represent two distinct and separable molecules, this need not be true for circular DNA. If the strands twist an odd number of times around one another in completing the DNA loop, then they are covalently joined into a single molecule.
See also