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': 'Which of the following gene is constitutively expressed in E.coli? \nSelect and explain. \nA. Lac A, B. Lac I, C. Lac Y, D. Lac Z', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Genes can be broadly divided into types based on their expression pattern: Constitutively expressed genes Regulated genes House-keeping genes Inducible/repressible Transcribed at a constant level Transcribed depending upon the environmental conditions Eg : Glycolytic enzymes Ribosomal RNA and proteins Eg : UDP-glucuronosyl transferase Lac I gene is constitutively regulated. Lac Z, Lac Y and Lac A genes are regulated by induction/repression.', 'role': 'assistant'}]