I was studying about conjugation in bacteria, I have a doubt. In conjugation F- cell transforms into F+ cell when there is a formation of sex pilli in between the two. The doubt is if the F- cells convert into F+ cells how can F- cells form again...?

If all the F- cells convert into F+ can we expect F- cells to form again?


1 Answer 1


Within a bacterial cell exists circular chromosomes, and plasmids. During cellular division, chromosomes are always conserved - passed to both daughter cells.

As you are aware, plasmids can be passed between cells by a form of horizontal gene transfer called conjugation - whereby plasmid DNA is replicated, and passed through a sex-pilli into an adjacent cell.

When a cell divides in to two daughter cells, it is possible that one cell will not receive a plasmid. Thus, the result is one F+ daughter cell, and one F- daughter cell.

  • $\begingroup$ The partitioning of the F plasmid between daughter cells is tightly regulated academic.oup.com/nar/article-lookup/doi/10.1093/nar/gkr457. Loss of F takes place if this mechanism fails. $\endgroup$
    – Alan Boyd
    May 27, 2017 at 10:12
  • $\begingroup$ That's an interesting article. But regardless of mechanism, I think the important point to OP's question is the fact that reversion to F- cells can occur during cellular replication. $\endgroup$
    – Bob
    May 27, 2017 at 15:34
  • $\begingroup$ Agreed, I was commenting on the (now deleted) use of the word 'stochastic' which conjured up a picture of a rather random process. Clearly it isn't. I certainly wasn't suggesting that loss of F can't happen, but I haven't found any data on how frequently it does happen. Probably that is to be found in very old literature. $\endgroup$
    – Alan Boyd
    May 27, 2017 at 15:42
  • $\begingroup$ As extra genes generally cause increased stress to a cell, unless the cell is actively taking advantage of plasmid DNA, I believe they will get rid of them. But I do disagree with your statement that plasmid replication does not ever display stochastic characteristic. sciencedirect.com/science/article/pii/… $\endgroup$
    – Bob
    May 27, 2017 at 16:02
  • $\begingroup$ What about the process of duplication of plasmids and the production of pilis? My understanding of comments is that it's connected: duplication of plasmids (that is not that trivial to me, should be mentioned) should be a prerequisite for sex pili transfer, so no pili without duplication? I mean, there's more than "never get lost on you" than a very good song. $\endgroup$ Feb 26, 2022 at 19:31

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