Question about Conjugation

[JP2740]

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For conjugation, a regular transfer between F+ and F- makes the F- into F+. Does this really mean anything besides making the F- into F+? Like it doesn't promote genetic diversity right?

As for Hfr, in the book it says the F- remains F-, and the genes around the F factor gene may be transferred along so this does promote genetic diversity while keeping the F- cell an F-. Right?

 

[IH8ColdWeath3r]

If I remember correctly, the reason that F- stays F- is because of the HFr plasmid because it occurs so rapidly that not all the genes are transferred appropriately. I think....but I may be wrong

 

[PiBond]

Conjugation does increase genetic diversity. When the bridge forms there is a transfer of genetic material that gives the new F+ new genetic material including, among other things, the ability to form a conjugation bridge.

 

[JP2740]

Conjugation does increase genetic diversity. When the bridge forms there is a transfer of genetic material that gives the new F+ new genetic material including, among other things, the ability to form a conjugation bridge.

Oh from the pictures in princeton it seems like all that's transferred is the plasmid.

 

[joshto]

Oh from the pictures in princeton it seems like all that's transferred is the plasmid.

all that's transferred is a plasmid--but a plasmid is genetic information.

 

[JP2740]

But how does that regarded as increasing genetic diversity if the only thing they get is the ability to form a conjugation bridge?

 

[rem6775]

F plasmid conjugation is basically what you described. A F+ bacteria conjugates with an F- one, with the necessary proteins for conjugation being encoded on the plasmid. Plasmids can encode simply these proteins, but they often have many genes, including ones for antibiotic resistance (penicillinase for example) or other virulence factors that may be important (exotoxins, fimbriae, etc.). Therefore, they are hugely important in the creation of resistant bugs. Even if the F plasmid only contained the genes for conjugation, Hfr conjugation could pass on important genes if excision of the plasmid occurs at a different site than integration and a segment of bacterial chromosome is passed on as well.

An Hfr cell is simply one with its F plasmid incorporated into the bacteria's chromosome. Two things can happen in Hfr conjugation:

1. It can undergo normal conjugation with transfer of the entire chromosome (including the F plasmid and the entire bacterial chromosome); or
2. the integrated plasmid may be excised at a different spot than where it was integrated resulting in an F plasmid that has some of the bacterial chromosome with it.

 

[JP2740]

But does the cell always remain F- in Hfr conjugation?

 

[rem6775]

I'm not sure I've read that anywhere specifically, but it seems if it's possible for the entirety of the plasmid (as well as the bacterial chromosome) to be transferred, it would seem they could become F+. I highly doubt that is anything you need to be worrying about though, to be honest.

 

[JP2740]

I'm really curious about it because that's what it shows in the TPRH book lol