(plăz'mĭd )

A piece of extrachromosomal, double-strand ed DNA found in most bacteria. Plasmids replicate when a bacterium divides and are passed to subsequent cells. The products of plasmid genes are enzymes that provide resistance to antibiotics or that synthesize bacteriocins or other toxins.

SYN: episome.

SEE: bacteriocin; transposon.