episome
Noun: A genetic element, specifically a segment of DNA, that can exist and replicate autonomously within a bacterial cell as an independent circular molecule, or can integrate into and replicate as part of the host cell's chromosome.
The term is used primarily in microbiology and molecular genetics to describe a specific type of extrachromosomal genetic material. * The bacterial episome carried genes for antibiotic resistance. * Researchers studied how the episome switched between its integrated and free-living states. * The presence of an episome can confer new traits to the host bacterium.
- The concept of an episome is central to understanding bacterial genetics and early genetic engineering techniques, as some plasmids and viral genomes can exhibit episomal behavior.
- In eukaryotic contexts (e.g., some viral DNA in animal cells), the term is sometimes used more loosely to describe non-integrated, replicating circular DNA, though "episomal" is the more common adjectival form in this usage.
- Episomal (adjective): Describing the state or nature of an episome.
- The virus maintained an episomal form in the host cell nucleus.
- Plasmid (noun): A more general term for a small, circular, extrachromosomal DNA molecule that replicates independently. Not all plasmids are episomes, but many episomes are plasmids.
- Integrate (verb): The action of an episome inserting itself into the host chromosome.
- Extrachromosomal genetic element
- Plasmid (in many, but not all, contexts)
The key distinguishing feature of an episome is its dual replication capability: it can exist independently or as part of the chromosome. This contrasts with a simple plasmid, which typically only replicates independently, and a prophage (integrated viral DNA), which is typically only integrated.
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DNA that is not incorporated into the genome but is replicated together with the genome (especially in bacterial cells)
