Plasmids

The word plasmid was firstly introduced in 1952 through the American molecular biologist Joshua Lederberg. In genetics and microbiology a plasmid is a DNA molecule which is divided from and can repeated independently of the chromosomal DNA. They are double-stranded and in various cases circular. The Plasmids generally occur naturally in bacteria but sometimes that are found in archaea and even in eukaryotic organisms foe example the 2-micrometre ring in Saccharomyces cerevisiae.

The Plasmid 1 to over 1,000 kbp sizes varies from. The number of identical plasmids in a single cell can range anywhere from one to 1000 under some circumstances. Plasmids can be measure part of the mobilome because they are often associated with conjugation a mechanism of horizontal gene transfer.

The Plasmids are considered replicons capable of repeating autonomously within a suitable host. It can be found in all three major domains that are Bacteria, Archaea and Eukarya. As same to viruses plasmids are not considered through some to be a form of life. Dissimilar to the viruses plasmids are naked DNA and do not encode genes compulsory to encase the genetic material for transfer to a new host by some classes of plasmids encode the sex pilus necessary for their own transfer. Plasmid host-to-host transfer needs direct mechanical transfer through conjugation or changes in incipient host gene expression allowing the intentional uptake of the genetic element through transformation.