How Does the Cro Protein from λ Phage Help to Establish

Question

How does the cro protein from λ phage help to establish a lytic infection?
A) It inhibits the integrase enzyme.
B) It activates the excision enzyme.
C) It binds to OL1 and blocks transcription from PL
D) It binds to OR1 and blocks transcription from PR
E) It binds to OR3 and blocks transcription from PRM.

Accepted Answer

The cro protein binds to O_R3, blocking transcription from P_RM, which prevents the production of the cI repressor, thus favoring the lytic cycle over the lysogenic cycle.