This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of lipid, Subject name: Biochemistry
[{'content': 'The reducing equivalents for cholesterol biosynthesis are provided by \nSelect and explain. \nA. FADH2, B. FMNH2, C. NADH, D. NADPH', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Cholesterol is a 27-carbon compound consisting of 4 rings and a side chain. It is synthesized from acetyl-CoA by a lengthy pathway that may be divided into five steps:(1) synthesis of mevalonate from acetyl-CoA (2) formation of isoprenoid units from mevalonate by a loss of CO2 (3) condensation of six isoprenoid unitsform squalene (4) cyclization of squalene gives rise to the parent steroid, lanosterol; (5) formation of cholesterol from lanosterol.NADPH provides the reducing equivalents.Ref: Harper&;s Biochemistry; 30th edition; Chapter 26; Cholesterol Synthesis, Transpo, & Excretion', 'role': 'assistant'}]