plasmid

noun

1. A loop of double-stranded DNA that is separate from — and replicates independently of — the chromosomes; such loops are most commonly found in bacteria, but they are also sometimes found in archaeans and eukaryotic cells, and they are used in genetic engineering as a vector for gene transfer.

   “These discussions have left a plethora of terms adrift: pangenes, bioblasts, plasmagenes, plastogenes, chondriogenes, cytogenes and proviruses, which have lost their original utility owing to the accretion of vague or contradictory connotations. At the risk of adding to this list, I propose plasmid as a generic term for any extrachromosomal hereditary determinant.”

   “This is how the F (for "fertility") plasmid, which forms the basis of a lot of classical E. coli genetics, is transferred from one cell to another.”

   “Bacteria are happy to absorb little rings of DNA called plasmids and adopt them as their own.”

   “Plasmids have an essential impact on productivity. Related factors are plasmid copy number, structural plasmid stability and segregational plasmid stability.”