This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Unaltered final product of TCA cycle ? \nSelect and explain. \nA. Oxaloacetate, B. Acetyl CoA, C. CO2, D. Pyrovate', 'role': 'user'}, {'content': 'Answer: A \nExplanation: TCA cycle consists of sequential reactions. It begins with condensation of four carbon oxaloacetate molecule with 2 carbon acetyl CoA molecule to form six carbon citrate molecule. In subsequent reaction two carbon atoms are lost in the form of CO2 at two different reactions. A series of modifications occur in the remaining four carbon atoms to ultimately form oxaloacetate. Thus the last substrate (oxaloacetate) of one cycle is ready for use as a substrate in the next cycle. In this way, there is no net generation of OAA, or of any of the cycle intermediates.', 'role': 'assistant'}]