You are using a gene fusion between a very bad gene (vbg) and lacZ to study the regulation of vbg by iron. (When lacZ is expressed, cells are blue; when lacZ is not expressed, cells are white.) You...

You are using a gene fusion between a very bad gene (vbg) and lacZ to study the regulation of vbg by iron. (When lacZ is expressed, cells are blue; when lacZ is not expressed, cells are white.) You introduce a transposon into the strain carrying a vbg-lacZ fusion and screen for regulatory mutants. You conclude that vbg is expressed in the presence of iron because you observe that, for the wild-type fusions, colonies are in the presence of iron and in the absence of iron. You conclude that the transposon has inserted into a gene encoding an activator protein because you observe that colonies are in the presence of iron and in the absence of iron.

A. blue ... white ... blue ... blue

B. white ... blue ... blue ... blue

C. blue ... white ... white ... white

D. white ... blue ... white ... white

E. white ... blue ... white ... blue