You are given two strains of E. coli. The Hfr strain is arg+ ala+ glu+ pro+ leu+ T s; the F− strain is arg − ala− glu− pro−leu− T r. All the markers are nutritional except T, which determines sensitivity or resistance to phage T1. The order of entry is as given, with arg+ entering the recipient first and T slast. You find that the F− strain dies when exposed to penicillin (pens), but the Hfr strain does not (penr). How would you locate the locus for pen on the bacterial chromosome with respect to arg, ala, glu, pro, and leu? Formulate your answer in logical, well-explained steps, and draw explicit diagrams where possible.

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Viral Replication

The virus is acellular and considered non-living outside the host cell. The replication of the virus occurs only inside the living cells. Only a few genes are present in the smallest virus, whereas many genes are present in the largest virus. These genes encode specific viral proteins.