This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lipids, Subject name: Biochemistry
The first step in fatty acid synthesis involves: 
Select and explain. 
A. Acetyl-CoA carboxylase, B. Hydroxyl-CoA dehydrogenase, C. Acetyl dehydrogenase, D. Pyruvate kinase
A: Acetyl-CoA carboxylase
Answer: A: Acetyl-CoA carboxylase 
Explanation: Ans. A. Acetyl-CoA carboxylase(Ref Harper 31/e page 217)Fatty Acid SynthesisBy two enzyme system1. Acetyl-CoA carboxylase2. Fatty acid synthase complexAcetyl-CoA CarboxylaseConverts acetyl-CoA (2C) to malonyl-CoA in the presence of ATP.Acetyl-CoA carboxylase has a requirement for the B vitamin biotin.It is a multienzyme protein.This is the rate limiting stepQ in the fatty acid synthesis.Acetyl-CoA carboxylase is not a part FAS ComplexQ.