This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'The sigma (s) subunit of prokaryotic RNA polymerase \nSelect and explain. \nA. Binds the antibiotic rifampicin, B. Is inhibited by a-amanitin, C. Specifically recognizes the promoter site, D. Is pa of the core enzyme', 'role': 'user'}, {'content': 'Answer: C \nExplanation: prokaryotic RNA polymers contain 2 alpha subunit, 2 beta subunit, 1 omega subunit, 1 sigma subunit and 2 zinc molecules Beta subunit fixes at the initiation siteThe sigma factor recognizes the promoter site and the affinity of the holoenzyme to the promoter siteRef: DM Vasudevan, 7th edition, page no: 589', 'role': 'assistant'}]