The fox operon, which has sequences A, B, C, and D (which may represent either structural genes or regulatory sequences), encodes enzymes 1 and 2. Mutations in sequences A, B, C, and D have the following effects, where a plus sign (+) indicates that the enzyme is synthesized and a minus sign (-) indicates that the enzyme is not synthesized. Fox present Mutation in sequence Enzyme 1 Enzyme 2 Enzyme 1 Enzyme Fox absent No mutation A D + +| | +

Can you think for how long the lack operon would be expreesed in the presence of lactose?

Describe two examples of regulators that acted on transcription at steps after initiation. Of the two examples, one must be from a phage system and the other from a bacterial biosynthetic operon.

Given the Table below concerning the lac operon, match the letter with what would be occurring for each scenario. Repressor is bound to the operator, cAMP complex is bound and transcription is prevented.   Allolactose is bound to the repressor, cAMP complex is bound, and transcription is prevalent.                                    Allolactose is bound to the repressor, cAMP complex is not assembled, and transcription is slow                        Repressor is bound to the operator, cAMP complex is not assembled, and transcription is prevented.