BCHM 561 final

BCHM 561 final - BCHM 561 EXAM IV Fall 2009 NAME(please...

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- 1 - NAME ( please print clearly ) Please write legibly in the space provided. If additional space is needed to write your answers, use the back of the pages provided making sure you include the question number. The total points assigned to each question are enclosed in brackets. There are a total of 200 points. There may be more than one correct selection for multiple choice questions. Circle all correct choices. Gluconeogenesis and the Citric Acid Cycle 1. [6] ( A ) What is gluconeogenesis? ( B ) Describe the principal physiologic role of gluconeogenesis in humans? 2. [4] The synthesis of glucose from pyruvate by gluconeogenesis: A. requires the oxidation of NADH B. requires the oxidation of FADH 2 C. involves the formation of ethanol D. requires the cofactor biotin E. both A and D above 3. [4] Which of the following organs are major sites of gluconeogenesis in humans? A. Liver B. Brain C. Pancreas D. Heart E. none of the above BCHM 561 EXAM IV Fall 2009 Gluconeogenesis is the biosynthesis of glucose from simple, noncarbohydrate precursors such as lactate, amino acids, or glycerol. Many precursors are converted to pyruvate or oxaloacetate, whereas other precursors, like glycerol, enter the pathway at later intermediates Gluconeogenesis along with glycogenolysis plays a crucial role in maintaining optimal blood glucose concentrations during periods of fasting, intense energy consumption (e.g. muscle contraction), or starvation.
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- 2 - 4. [12] Three steps in glycolysis are highly exergonic and are essentially irreversible, thus gluconeogenesis does not occur by the simple reversal of glycolysis. To carry out the conversion of pyruvate to glucose, several enzymes unique to gluconeogenesis must bypass or overcome these three irreversible reactions of glycolysis. List below the names of the enzymes of glycolysis that catalyze the three exergonic steps and for each give the name of the enzyme(s) from gluconeogenesis that circumvent these irreversible reactions. Enzymes of Glycolysis Enzymes of Gluconeogenesis 5. [8] Write the complete reactions used by animals to convert pyruvate to phosphoenolpyruvate in gluconeogenesis? Give the name of the enzymes catalyzing each reaction and include all cofactors. ( complete chemical structures are not required ) 6. [4] What is the net energetic cost of converting two pyruvate to one glucose by gluconeogenesis in terms of ATP equivalents? A. 2 B. 4 C. 6 D. 8 7. [4] How does the activity of the enzyme fructose 1,6-bisphosphatase respond to a large increase in the concentration of fructose 2,6-bisphosphate? A. it increases B. it decreases C. it is unchanged (1) Hexokinase Glucose 6-phosphatase (2) Phosphpfructokinase-1 Fructose 1,6-bisphosphatase (3) Pyruvate kinase Pyruvate Carboxylase Phosphoenolpyruvate (PEP) carboxykinase Pyruvate + CO 2 + ATP +H 2 O oxaloacetate + ADP + P i + 2 H + Oxaloacetate + GTP phosphoenolpyruvate + GDP + CO 2 Pyruvate Carboxylase Phosphoenolpyruvate (PEP) Carboxykinase
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- 3 - 8. [4] How does the activity of the enzyme
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This note was uploaded on 02/02/2010 for the course BCHM 561 taught by Professor Mr. during the Spring '10 term at Purdue.

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BCHM 561 final - BCHM 561 EXAM IV Fall 2009 NAME(please...

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