This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Basics of genetics, Subject name: Biochemistry
[{'content': 'The ZYA region of the lac operon will be maximally expressed if: \nSelect and explain. \nA. Cyclic AMP levels are low, B. Glucose and lactose are both available, C. The attenuation stem-loop is able to form, D. The CAP site is occupied and the operator site is free', 'role': 'user'}, {'content': 'Answer: D \nExplanation: When the cAMP levels are low- there is no binding of CAP to CAP site. | No ourable interaction for RNA polymerase. | Lac operon is not expressed. - option a is excluded. When glucose is available, Lac operon is not expressed Attenuation is seen in tryptophan operon, not Lac operon For optimal expression of lac operon, The CAP site should be occupied the operator site should be free of repressor.', 'role': 'assistant'}]