Final answer:
Gene expression in bacteria is regulated by induction and repression. The lac operon and trp operon are examples of this regulation. The lac operon is induced by lactose and repressed by the lac repressor protein, while the trp operon is repressed by tryptophan.
Step-by-step explanation:
The regulation of gene expression in prokaryotic cells occurs at the transcriptional level. Bacterial genes are often organized into operons, such as the lac operon and the trp operon. The lac operon is an example of gene regulation through both induction and repression. When lactose is present, it acts as an inducer, binding to the lac repressor protein and causing it to release from the operator. This allows RNA polymerase to bind to the promoter and transcribe the genes involved in lactose metabolism. On the other hand, the trp operon is regulated by gene repression. When tryptophan is present, it binds to the trp repressor protein, allowing it to bind to the operator and block transcription of the genes involved in tryptophan synthesis.