Figure 16.5 In E. coli, the tip operon is on by default, while the lac operon is off. Why do you think that this is the case? In the absence of lactose, the lac repressor binds the operator, and transcription is blocked.

You are growing E. coli in a laboratory in order to study their operons. The growth media you are using contains lactose, no glucose and no tryptophan.  Using your knowledge of operons and their regulation, answer the following questions  Which operons would be functional under these conditions?   2. What repressors would be made? (NOTE: name the repressors using their gene names)   3.Which repressor(s) would be made in the inactive form?   4.Which repressor(s) would be made in the active form?   5.Which repressor(s) under these conditions can bind the operator sequence?   6.Which repressor(s)under these conditions cannot bind the operator sequence?

If a researcher moves the promoter for the lac operon to the region between the beta galactosidase (lacZ) gene and the permease (lacY) gene, which of the following results would you expect? A) The three genes of the lac operon will be expressed normally. B) The repressor will not be able to bind to the operon. C) The operon will still transcribe the lacZ and lacY genes, but the mRNA will not be translated. D) LacZ will not be transcribed and Beta galactosidase will not be produced.

The lac operon is an inducible operon. What does this mean?