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:
“If one doubts whether Grecian valor and patriotism are not a fiction of the poets, he may go to Athens and see still upon the walls of the temple of Minerva the circular marks made by the shields taken from the enemy in the Persian war, which were suspended there. We have not far to seek for living and unquestionable evidence. The very dust takes shape and confirms some story which we had read.”
—Henry David Thoreau (1817–1862)
“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)