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
Rate limiting step in Gluconeogenesis is catalyzed by 
Select and explain. 
A. Phyruvate Carboxylase, B. Glucokinase, C. Glycoral kinase, D. PDH
A: Phyruvate Carboxylase
Answer: A: Phyruvate Carboxylase 
Explanation: Key Gluconeogenic Enzymes 1.Pyruvate carboxylase. 2. Phosphoenolpyruvate carboxykinase 3.Fructose-1-6-bisphosphatase 4.Glucose-6-phosphatase in the cytoplasm enters the mitochondria. Then, carboxylation of pyruvate to oxaloacetate is catalysed by a mitochondrial enzyme, pyruvate carboxylase (Fig. 9.24). It needs the co-enzymes biotin and ATP.Ref: DM Vasudevan, 7th edition, page no: 117