Essential Genetics 6th Edition by Daniel Hartl

Exercise 16

The order of the genes in the bacteriophage l is A B C D E att int xis N CI O P Q S R.
(a) Given that the bacterial attachment site, att , is between gal and bio in the bacterial chromosome, what is the prophage gene order?
(b) A mutant phage is discovered that has the reverse gene order in the prophage as in the wildtype prophage. What does this say about the orientation of the att site in regard to the termini of the phage chromosome?
(c) A wildtype ? lysogen is infected with another ? phage carrying a genetic marker, Z , located between E and att. The superinfection gives rise to a rare, doubly lysogenic E. coli strain that carries both ? and ? Z prophage. Assuming that the second phage also entered the chromosome at an att site, diagram two possible arrangements of the prophages in the bacterial chromosome and indicate the locations of the bacterial genes gal and bio.