, ▁the ▁ph age ▁may ▁immediately ▁proceed ▁to ▁the ▁l yt ic ▁phase ▁or ▁it ▁may ▁enter ▁a ▁l ys ogen ic ▁state . ▁ ▁The ▁gene ▁that ▁enc odes ▁the ▁tail ▁fib ers ▁have ▁a ▁set ▁of ▁sequences ▁that ▁can ▁be ▁target ed ▁by ▁a ▁site ▁specific ▁recom bin ase ▁Cin . ▁This ▁causes ▁the ▁C ▁terminal ▁end ▁of ▁the ▁protein ▁to ▁switch ▁between ▁two ▁alternate ▁forms ▁at ▁a ▁low ▁frequency . ▁The ▁vir al ▁tail ▁fib ers ▁are ▁responsible ▁for ▁the ▁specific ity ▁of ▁binding ▁to ▁the ▁host ▁re ceptor . ▁The ▁targets ▁of ▁the ▁vir al ▁tail ▁fib ers ▁are ▁under ▁a ▁constant ▁pressure ▁to ▁evol ve ▁and ▁e va de ▁binding . ▁This ▁method ▁of ▁recom bin ational ▁divers ity ▁of ▁the ▁tail ▁allows ▁the ▁virus ▁to ▁keep ▁up ▁with ▁the ▁b acter ium . ▁This ▁system ▁has ▁close ▁sequence ▁hom ologies ▁to ▁recom bin ational ▁systems ▁in ▁the ▁tail ▁fib ers ▁of ▁un related ▁ph ages ▁like ▁the ▁mu ▁ph age ▁and ▁the ▁lambda ▁ph age . ▁ ▁L ys ogen y ▁The ▁gen ome ▁of ▁the ▁P 1 ▁ph age ▁is ▁maintained ▁as ▁a ▁low ▁copy ▁number ▁pl as mid ▁in ▁the ▁b acter ium . ▁The ▁relatively ▁large ▁size ▁of ▁the ▁pl as mid ▁requires ▁it ▁to ▁keep ▁a ▁low ▁copy ▁number ▁l est ▁it ▁become ▁too ▁large ▁a ▁met abol ic ▁bur den ▁while ▁it ▁is ▁a ▁l ys ogen . ▁As ▁there ▁is ▁usually ▁only ▁one ▁copy ▁of ▁the ▁pl as mid ▁per ▁b