NAME NETWORK ID MCB 450 Fall 2014 Exam III November 6th 2014 Form A Choose the BEST answer from the available choices Only non graphing calculators are permitted for use on this exam Section 1 29 Multiple choice Questions Each question is worth 4 points 1 The reactions below have the following standard free energy changes 1 3 bisphosphoglycerate 3 phosphoglycerate Pi G 49 4 kJ mol ATP ADP Pi G 30 5 kJ mol What is the overall G for the following reaction 1 3 bisphosphoglycerate ADP 3 phosphoglycerate ATP a 18 9 kJ mol b 18 9 kJ mol c 40 0 kJ mol d 79 9 kJ mol e 79 9 kJ mol 1 NAME NETWORK ID 2 The ultimate product of complete oxidation of carbohydrates is a O2 b CO2 c acetyl CoA d pyruvate e acetate ion 3 A reaction that best serves as a control point in metabolic pathways a is a near equilibrium reaction b has a large positive G c is metabolically irreversible d follows Michaelis Menten kinetics e is endergonic 4 ATP is thermodynamically suited as a carrier of phosphoryl groups in animal cells because a it is kinetically stable under cell conditions b it is not hydrolyzed in cells without enzyme action c it is intermediate in group transfer potential d it is thermodynamically unstable under cell conditions e All of the above choices are correct 5 Which of the following reactions is are thermodynamically more favorable then the ATP hydrolysis reaction a Phosphoenolpyruvate PEP to pyruvate b 2 Phosphoglycerate to phosphoenolpyruvate PEP c 1 3 Bisphosphoglycerate to 3 phosphoglycerate d Acetyl CoA to acetate and CoA e Answer choices a and c are both correct 2 NAME NETWORK ID 6 The catabolism of 1 mole of glucose to lactate in the glycolytic pathway is accompanied by the reduction of how many moles of O2 a 0 b 2 c 4 d 6 e 8 7 The conversion of 1 mol of fructose 1 6 bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of a 1 mol of NAD and 2 mol of ATP b 1 mol of NADH and 1 mol of ATP c 2 mol of NADH and 2 mol of ATP d 2 mol of NADH and 4 mol of ATP e 2 mol of NAD and 4 mol of ATP 8 Which of the following is NOT an intermediate of the glycolytic pathway a 1 3 bisphosphoglycerate b Pyruvate c 2 phosphoglycerate d Fructose 1 phosphate e Phosphoenolpyruvate 9 Which is NOT among the possible fates of pyruvate after glycolysis a Conversion to alanine b Reduction of its carbons by the citric acid cycle c Conversion to ethanol d Conversion to oxaloacetate e Conversion to lactate 3 NAME NETWORK ID 10 Glucokinase has a Km value of 10 0 mM whereas hexokinase has a Km value of 0 1 mM This is consistent with which of the following a Glucokinase acts on glucose at low glucose concentrations b Glucokinase acts on glucose only at high glucose concentrations c Glucokinase phosphorylates most of the glucose at low glucose levels d Hexokinase acts on glucose only at high levels of glucose e Hexokinase acts at about half maximal velocity at glucose concentrations of 4 5 mM 11 Hamsters love to run on exercise wheels Prolonged running at a high rate of speed requires ATP Could a hamster with a defective gene for the muscular form of the enzyme lactate dehydrogenase meet the extra ATP demand for prolonged fast wheel running by maintaining a high rate of glycolysis when muscles are operating under anaerobic conditions Why or why not a No not enough NAD can be regenerated for glycolysis to continue at a high rate b No the defective gene will cause accumulation of NAD which in turn will inhibit glycolysis c Yes the defective enzyme has no effect on the glycolytic pathway d Yes the enzyme alcohol dehydrogenase will supply the needed NAD if the lactose dehydrogenase cannot e Yes the extra pyruvate synthesized by the muscles can be converted to lactate by the liver 12 The products of the pathway whose first enzyme is glucose 6 phosphate dehydrogenase are CO2 and a 2 NADH 1 pentose phosphate b 2 NADH 1 hexose phosphate c 2 NADP 1 pentose phosphate d 2 NADPH 1 hexose phosphate e 2 NADPH 1 pentose phosphate 4 NAME NETWORK ID 13 ATP is a co substrate of the enzyme phosphofructokinase PFK PFK 1 In most species ATP is also an inhibitor of PFK 1 at higher concentrations Which statement below would provide a suitable explanation for this discrepancy a PFK 1 must be phosphorylated by ATP in the active site and the phosphorylated PFK 1 must be the less active form b There must be another cofactor interacting with ATP at high concentrations to achieve inhibition of PFK 1 c ATP actually activates the reverse of the reaction preceding the PFK 1 step in the pathway It likely has no direct effect on PFK 1 d There are two sites on PFK 1 that bind ATP One is the active site the other is the regulatory site where inhibition occurs e ATP is unable to bind to the allosteric site on PFK at high concentration 14 All of the following are substrates for gluconeogenesis EXCEPT a Fatty acids b Glycerol c Oxaloacetate d Lactic acid e Alanine 15 Which of the following is the correct statement regarding gluconeogenesis a Fructose 2 6 bisphosphate and AMP positively regulate gluconeogenesis b Citrate and ATP negatively regulate gluconeogenesis c Fructose 2 6 bisphosphate and citrate positively regulate gluconeogenesis d Citrate and AMP negatively regulate gluconeogenesis e Citrate and acetyl CoA positively regulate gluconeogenesis 5 NAME NETWORK ID 16 Which of the following reactions is NOT part of the pentose phosphate pathway a C5 C5 C3 C7 by the enzyme transketolase b C4 C5 C3 C6 by the enzyme transketolase c C3 C7 C6 C4 by the enzyme transaldolase d C4 C6 C5 C5 by the enzyme transaldolase e All of the above reactions are part of the pentose phosphate pathway 17 When a cell with an active pentose phosphate pathway has need for more ribose 5 phosphate but no additional NADPH a Glucose 6 phosphate dehydrogenase is activated b The oxidative and non oxidative enzymes of the pentose phosphate pathway are active c The non oxidative enzymes produce pentose phosphates from fructose 6 phosphate and glyceraldehyde 3 phosphate d All enzymes of glycolysis and pentose phosphate pathway are active e None of the above choices are true 18 Below is a list of the coenzymes used by the pyruvate dehydrogenase complex and their role Select the coenzyme which is mismatched to its role a Thiamine pyrophosphate transfers acetyl group to E3 b NAD accepts electrons from FADH2 c Coenzyme A accepts the acetyl group from lipoic acid d Thiamine pyrophosphate plays role in the decarboxylation of pyruvate e FAD accepts electrons from
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