Genetics: Analysis and Principles 5th Edition by Robert Brooker

Exercise 37

Certain environmental conditions such as UV light are known to activate lysogenic prophages and cause them to progress into the lytic cycle. UV light initially causes the repressor protein to be proteolytically degraded. Make a flow diagram that describes the subsequent events that would lead to the lytic cycle. Note: The xis gene codes for an enzyme that is necessary to excise the prophage from the E. coli chromosome. The integrase enzyme is also necessary to excise the prophage.