Most prokaryotes carry a small amount of genetic material in the form of a single molecule, or chromosome, of circular DNA. The DNA in prokaryotes is contained in a central area of the cell called ...

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.

Circular DNA, thought to be an accidental byproduct, is borrowing the cell’s DNA repair mechanisms to copy itself DURHAM, N.C. -- Like its viral cousins, a somewhat parasitic DNA sequence called a ...