Many prokaryotes also carry small, circular DNA molecules called plasmids, which are distinct from the chromosomal DNA and can provide genetic advantages in specific environments.

For instance, in many cases, conjugation serves to transfer plasmids that carry antibiotic resistance genes.

Genetic material DNA in a nucleus, plasmids are found in a few simple eukaryotic organisms. DNA is a single molecule, found free in the cytoplasm; additional DNA is found on one or more rings ...