How does the lac operon regulate the production of the enzymes needed to metabolize lactose? Summarize the key ideas and concepts in list format.

The lac operon regulates the production of the enzymes needed to metabolize lactose in the following ways: • In the absence of lactose, the upstream lacI gene synthesizes the lac repressor protein, which binds to the lac operator to stop RNA polymerase from binding and stop the transcription of the lacZ, lacY, and lacA genes that code for the proteins involved in lactose metabolism. • When lactose is made available to the cell, some of it binds to the lac repressor protein, inactivating it so that it cannot bind to the operator. • This allows RNA polymerase to bind to the promoter, and allows the transcription of the downstream lacZ, lacY, and lacA genes. • Translation of the mRNA produces the three lactose-metabolizing enzymes. • If lactose is removed from the cell’s environment, the repressor will become active and will bind to the operator, preventing further transcription of the lactose metabolizing genes.