episome

Term: episome

Origin: Anc Greek

επί-/epi(=as a prefix means

               1. over, upon, at, towards, during

               2. besides

               3. cause

+σώμα/soma(=body)

Literally meaning : additional to body (chromosome)

Coined/History

by Jacob and Wollman in 1961, as a genetic factor that can persist in both the intgrated state and as an extrachromosomal replicon in host cells.

Definition

An episome is a portion of genetic material that can exist either autonomously in the cytoplasm or as part of a chromosome, especialy in bacteria. Examples of episomes include insertion sequences and transposons, viruses, and the bacterial sex plasmid F.