Self-replicating, circular DNA molecules found in bacterial cells; often used as vectors in recombinant DNA technology. Small circles of double-stranded DNA found in some bacteria. Plasmids can carry from four to 20 genes. Plasmids are a commonly used vector in recombinant DNA studies. PICTURE
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organsim to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
A structure composed of DNA that is separate from the cell's genome. In bacteria, plasmids confer a variety of traits and can be exchanged between individuals - even those of different species. Plasmids can be manipulated in the laboratory to deliver specific genetic sequences into a cell. Source : PhRMA Genomics