Plasmid?

Plasmids are circular DNA molecule present in the cytoplasm of bacteria, capable of autonomous replication (independent replicons). By their ability to transfer genes from one cells to another , plasmids have become impoant vectors in genetic engineering . Plasmids may also be seen in yeasts, which are eukaryotes . plasmid DNA may sometimes be integrated with chromosomal DNA . The name episome was employed for such integration forms,though this distinction is not usually made now. plasmids have been classified in many ways depending on whether they are self transmissible or nontransmissible on the propey encoded by restriction endonuclease finger printing or other criteria. REF:Ananthanarayan and Panicker's Textbook ofMicrobiology 8thEdition pg no:60