Intermediary Metabolism — DU B. Sc. (Hons) Biochemistry Previous Year Question Papers

There are 8 questions. (A) Define the following : (a) Multienzyme complex (b) Fatty acid activation (d) Fasting blood sugar (e) Amphibolic pathway. (B) Indicate whether true or false with justification : (a) The reactions of glycolysis occur only in the mitochondrial matrix. (b) Reduced coenzymes are a source of energy. (c) B-Oxidation of fatty acids is an energy-yielding process. (d) Triacylglycerol is an ideal storage molecule. (e) Liver glycogen is the source of blood glucose. 5,10 Differentiate between the following : (a) Preparatory and payoff phase of glycolysis. (b) Krebs bicycle and the Glucose-Alanine cycle. (c) Role of Insulin and Glucagon in sugar metabolism. 5x3 Write short notes on the following : Urea cycle (c) Pyruvate dehydrogenase complex. 5×3 Give reasons for the following : (a) The pentose phosphate pathway is overactive in the adipose tissue. (b) Urea cycle is energetically inexpensive. (c) Deficiency of Glucose-6-phosphatase can be of serious consequences. (d) Transaminases are clinically significant. (e) HGPRT is a key enzyme in the purine salvage pathway. 3x5 Identify the disease and discuss the biochemical basis of the disease : (b) Ketoacidosis is observed in an adult patient along with polyuria, polyphagia and polydipsia. (c) Swelling of joints and high levels of uric acid in the blood of the patient. (d) Excessive phenylalanine is found in the blood of a young child who is intellectually disabled. (e) Presence of high blood sugar, severe fatigue, increased thirst, weight loss seen in middle aged adults. 3x5 6. Answer the following : (a) Discuss the importance of the TCA cycle and its regulation. (b) Explain the reciprocal regulation of glycolysis and gluconeogenesis. (c) What are the metabolic shifts that occur during the starvation state ? 5x3 (a) How are fatty acids activated for their breakdown ? Explain the mechanism. (b) Explain the role of triacyl glycerol as an energy source. (c) Explain the Glycerol-3-phosphate shuttle. Why is it considered an expensive shuttle ? 5x3 8. (a) Show stepwise the number of ATP produced by the complete oxidation of palmitic acid. (b) Explain the different fates of pyruvate in living systems. (c) How is uric acid synthesized by the degradation of purines ? 5x3