The cells can also contain a drug resistance gene Y under {HEAD ~ control} of {TAIL ~ P} 
of
The cells can also contain a drug resistance gene Y under { HEAD ~ control } of { TAIL ~ P }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL