Is there a difference between an F' plasmid that has taken up a chromosomal gene that conveys antibiotic resistance, and an R plasmid? Is a bacterium containing an R plasmid and yet lacking an F+ plasmid capable of horizontal gene transfer by conjugation?

  • $\begingroup$ Can’t help myself …relevant (but here the better word would be “explanation”). Ed Yong thinks to, too. $\endgroup$ Feb 14, 2012 at 23:08
  • $\begingroup$ Explanation isn't really the word I'm looking for, as I do know what the terms mean individually, but not in relation to each other. I'll edit it to read "distinction". $\endgroup$ Feb 15, 2012 at 0:08

1 Answer 1


If I understand the nomenclature correctly, an R plasmid is just any plasmid containing an antibiotic (R)esistance gene (eg. Amp, Kan, Cm, etc.). It's a bit of an outdated name from when people didn't know how exactly the plasmids conferred such resistance.

An F-plasmid is any plasmid that contains the genes necessary for (F)ertility, eg:horizontal gene transfer via the tra operon.

The two do not have to appear together -- eg: Many F plamids will contain resistance genes (along with other random chunks from the genome), but resistance doesn't always have to be part of the payload. Likewise, it is common in labs to build pure resistance vectors that lack any horizontal transfer capability in order to select for particular clones.


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