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.
Famous quotes containing the words circular and/or dna:
“Whoso desireth to know what will be hereafter, let him think of what is past, for the world hath ever been in a circular revolution; whatsoever is now, was heretofore; and things past or present, are no other than such as shall be again: Redit orbis in orbem.”
—Sir Walter Raleigh (1552–1618)
“Here [in London, history] ... seemed the very fabric of things, as if the city were a single growth of stone and brick, uncounted strata of message and meaning, age upon age, generated over the centuries to the dictates of some now all-but-unreadable DNA of commerce and empire.”
—William Gibson (b. 1948)