Phage lambda enters the cell and integrates into the host cell by reciprocal recombination at a preferred site between bio and gal on the E. coli chromosome. Aberrant excision from the host chromosome can generate specialised transducing phage. Lambda attachment sitesPhage lambda enters the cell and integrates into the host cell by reciprocal recombination at a preferred site between bio and gal on the E. coli chromosome. Aberrant excision from the host chromosome can generate specialised transducing phage. Lambda attachment sites