Question

The lac operon consists of several genes that encode enzymes required for metabolizing lactose. The expression of the lac operon is regulated by the presence of lactose and glucose.

Q) describe the regulation operon when the level of glucose is high and the level of lactose is high?

Answer 1

Solution

regulation of operon when level of glucose is high

When level of glucose is to high, No transcription of the lac operon occurs. Because the lac repressor remains bound to the operator and prevents transcription by RNA polymerase. Also, cAMP levels are low because glucose levels are high, so CAP is inactive and cannot bind DNA. So glucose binds to and deactivates the repressor, preventing it from binding to the DNA.

regulation of operon when level of lactose is high

If lactose level is to high , the lac genes are expressed because allolactose binds to the Lac repressor protein and keeps it from binding to the lac operator. Allolactose is an isomer of lactose. ... RNA polymerase can then bind to the promoter and transcribe the lac genes. in lac operon there are three genes are present. lacZ,lacY and lacA. The three genes of the lac operon can be expressed and their subsequent proteins translated: lacZ, lacY, and lacA. The gene product of lacZ is β-galactosidase which breack lactose, a disaccharide, into glucose and galactose. lacY encodes Beta-galactoside permease, a membrane protein which becomes embedded in the cytoplasmic membrane to enable the cellular transport of lactose into the cell. Finally, lacA encodes Galactoside acetyltransferase.