Q13: In the case of Lac operon, the presence of glucose... - Cell Biology, Genetics, Physiology, Biochemistry & Plant Protection - ICAR AIEEA PG 2024 - Plant Sciences | Agrigyan

विस्तृत व्याख्या:

Catabolite Repression of the Lac Operon (अपचयी दमन):

• In E. coli, when glucose is readily available in the medium, the cell prefers glucose as its carbon/energy source over lactose.
• High glucose levels inhibit adenylate cyclase, resulting in very low levels of cyclic AMP (cAMP).
• Without sufficient cAMP, the CAP (Catabolite Activator Protein) or CRP cannot bind cAMP to form the active cAMP-CAP transcriptional activator complex.
• As a consequence, RNA polymerase binds very weakly to the promoter, preventing high-level transcription of the lac genes even if lactose is present.
• This phenomenon is universally known as Catabolite Repression (the 'glucose effect').

Correct Answer: Option 2 (Catabolite repression).