This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of carbohydrate, Subject name: Biochemistry
Pyruvate is conveed to which substance to sta gluconeogenesis? 
Select and explain. 
A. Oxaloacetate, B. Phosphenol pyruvate, C. Cis-aconitate, D. Succinate
A: Oxaloacetate
Answer: A: Oxaloacetate 
Explanation: GLUCONEOGENESIS 1. Definition - It is the process by which glucose molecules are produced from non-carbohydrate precursors. These include lactate, glucogenic amino acids, glycerol pa of fat and propionyl CoA derived from odd chain fatty acids. 2. Site - Gluconeogenesis occurs mainly in the liver, and to a lesser extent in the renal coex. The pathway is paly mitochondrial and paly cytoplasmic. 3. Key Gluconeogenic Enzymes - Pyruvate carboxylase, Phosphoenol pyruvate carboxy kinase, Fructose-1-6-bisphosphatase, Glucose-6-phosphatase. 1. Pyruvate Carboxylase Reaction - Pyruvate in the cytoplasm enters the mitochondria. Then, carboxylation of pyruvate to oxaloacetate is catalysed by a mitochondrial enzyme, pyruvate carboxylase. It needs the co-enzymes biotin and ATP. REF:DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY,EIGHTH EDITION,PG.NO.,136.