Ok so I'm having a bit of trouble understanding the whole concept of hfr cells. The way I see it, usually the F factor in F+ bacteria is on an extrachromosomal plasmid, which replicates and transfers to the F- bacteria during conjugation (ONLY the F factor plasmid can be transferred). I'm also reading that this F factor can incorporate itself into the bacterial chromosome in some bacteria (which are called hfr bacteria), so that during conjugation the MAIN chromosome can actually replicate and transfer genes to an F- bacterium. However, in this situation, the F factor does NOT always get transferred. Is this correct?? Or am I missing something? Clarification would be greatly appreciated! thanks!