Homologous recombination - (Dec/02/2005 )

Hi,
I am reading an article where they are using homologous recombination to insert a plasmid in a genome at a specific location.
The plasmid encode part of a gene which is homologue to a sequence in the actual genome. My understanding of homologous recombination is that you can exchange gene parts placed between homologue sequences.
Now in this article they have a plasmid which has a small part of a gene sequence in it. In that plasmid is also a resistance gene. But no other homologue sequence that the small gene part in one single place in the plasmid. My question is then, how does that allow one to insert the entire plasmid into the genome?
Thank you very much in advance,
Stegger

The cross-over event integrates the plasmid into the chromosome:

<----[wt5'wt3']----->

to:

<----[wt5'][ins5']vvvvvvvvvvvvvvvvvvvvvvvvvvvvvv[ins3'][wt3']---->

where <---> is meant to indicate the chro,osome, [wt5'wt3'] is the target gene, [ins5'ins3'] is the vector-encoded homologous insert DNA, and where v is the vector....