The model virus bacteriophage λ (lambda) has been used extensively to study the lysogenic mechanism.The virus genome includes genes that encode the regulator proteins cI and Cro, which compete for specific promotors on the viral DNA-including their own promotors.Cro and cI have opposite effects on each promotor: cI represses the expression of genes involved in the lytic cycle and promotes expression of genes involved in lysogeny, whereas Cro does the opposite.Suppose a mutation in Cro increases its expression.This mutation would make entering lysogeny _______ likely.A mutation that increases the expression of cI would have _______ effect on the likelihood of the virus entering lysogeny.

Question

Quizplus · Accepted Answer

A mutation in Cro that increases its expression would make entering lysogeny less likely, because Cro promotes the lytic cycle and inhibits lysogeny. Conversely, a mutation that increases the expression of cI would have the opposite effect, making entering lysogeny more likely.

The Model Virus Bacteriophage λ (Lambda) Has Been Used Extensively