Definition of plasmid in English:

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Pronunciation: /ˈplazmid/


A genetic structure in a cell that can replicate independently of the chromosomes, typically a small circular DNA strand in the cytoplasm of a bacterium or protozoan. Plasmids are much used in the laboratory manipulation of genes. Compare with episome.
Example sentences
  • The bacterium contains a plasmid, a circular piece of DNA that holds the gene and promoter sequence.
  • The replication control genes of bacterial plasmids face selection at two conflicting levels.
  • We note, however, that few if any of the genes borne by bacterial plasmids are under strong positive selection at all times.


1950s: from plasma + -id2.

For editors and proofreaders

Syllabification: plas·mid

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