Midterm2 w10


Published on

Published in: Education
  • Be the first to comment

  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Midterm2 w10

  1. 1. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .Question 1 (21 points): Fill in the missing information into the pathway of glycolysis(into the boxes). Include the name and chemical formula of the missing intermediates,the name of the missing enzymes, and if applicable the conversion of cofactors. Page 1 of 7
  2. 2. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .Question 2 (5 points):List two pathways in which Glucose-6-phosphate occurs as an intermediate. Describehow the utilization of Glucose-6-phosphate is regulated. To gain the full number ofpoints you need to include specific details (e.g. the names of key enzymes and someimportant allosteric activators/inhibitors).Question 3 (4points):Some individuals have a genetic deficiency of the enzyme triose phosphate isomerase(TIM). How does the absence of this enzyme affect the energy production fromglycolysis? Page 2 of 7
  3. 3. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .PART II: Use the scantron and a pencil to mark the correct answers of thefollowing multiple choice and true/false questions. Don’t forget to write yourname and netid on the scantron.Multiple choice: (2points each)Question 1: The biosynthesis of biomolecules from simpler components is called A) Catabolism B) Anabolism C) Metamorphosis D) EnzymologyQuestion 2: One highly exergonic reaction in a pathway makes the entire pathway A) Oxidative B) Reversible C) Irreversible D) ReductiveQuestion 3: Which item listed below is indicative for a catabolic pathway? A) consumes ATP B) involves the cofactor NAD+ C) results in the reduction of compounds using NADPH D) Both, A and C.Question 4: The overall ΔG value for glycolysis is -72kJ/mol in erythrocytes. Whichstatement below is true? A) The value of ΔGº’ is also -72 kJ/mol since the cellular pH is close to 7. B) The negative sign of ΔG shows that glycolysis is an endergonic process. C) The negative sign of ΔG shows that this pathway will proceed toward product (pyruvate) under normal cellular conditions. D) All of the above.Question 5: Where does ATP hydrolysis rank among the standard free energies ofphosphoryl group transfer of all biological molecules? A) A. ATP hydrolysis has the largest negative free energy change. B) B. ATP hydrolysis has nearly the smallest negative free energy change. C) C. ATP hydrolysis has nearly the largest negative free energy change. D) D. ATP hydrolysis has an intermediate free energy change. Page 3 of 7
  4. 4. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .Question 6:What is a valid chemical reason for the negative energy of hydrolysis ofphosphoric acid anhydride linkages for compounds such as ATP, ADP, andpyrophosphate? A) Phosphor-anhydride bonds are unstable because of the electrostatic repulsion between negatively charged phosphate neighbors. B) Hydrolysis products have better resonance stabilization C) Hydrolysis products have higher solvation energy D) All of the above.Question 7: In the equation, which is the oxidizing agent? A) Ethanol B) H+ C) Acetaldehyde D) NAD+ E) NADHQuestion 8:The standard free energy change (ΔG0’) for hydrolysis ofphosphoenolpyruvate (PEP) is -61.9 kJ/mol. The standard free energy change (ΔG0’) forhydrolysis of ATP is -30.5 kJ/mol.What is the standard free energy change for the pyruvate kinase reaction? A) -31.4 kJ/mol B) + 31.4 kJ/mol C) -92.4 kJ/mol D) + 92.4 kJ/molQuestion 9:The rate of which glycolytic enzyme shown below is not used to control therate of glycolysis? A) phosphofructokinase B) pyruvate kinase C) triose phosphate isomerase D) hexokinaseQuestion 10: Which pathways have oxaloacetate as an intermediate? A) Glycolysis B) Gluconeogenesis C) Citric acid cycle D) A and B E) B and C Page 4 of 7
  5. 5. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .Question 11:The free energy change ΔGº’ for the formation of ATP from ADP andinorganic phosphate is + 30.5 kJ/mol. Which reaction can drive the formation of ATPunder biochemical standard state conditions? A) Hydrolysis of glucose-6-phosphate (ΔGº’ = -13.9 kJ/mol) B) Hydrolysis of creatine phosphate (ΔGº’ = -43.3 kJ/mol) C) Both, A and B, can drive the formation of ATP. D) None of the above.Question 12: Which of the following statements about glycogen is false? A) Glycogen is a polymer of glucose in (α1 4) linkages with (α1 6) linked branches every 8–12 residues. B) Glycogen is the storage polysaccharide in skeletal muscle and liver cells. C) UDP–glucose is produced from glycogen by the action of the enzyme phosphorylase. D) In glycogen breakdown, glucose residues are sequentially removed from the nonreducing ends. E) The breakdown of glycogen in skeletal muscle ultimately supplies glucose-6- phosphate, which can enter glycolysis to generate ATP.Question 13: Glycogen synthesis in vertebrates requires the activation of glucose to A) UDP-glucose B) ADP-glucose C) Glucose-6-phosphate D) Glucose-1,6-bisphosphateQuestion 14:Which statement is correct? A) The citric acid cycle is also called the hexose monophosphate shunt. B) The citric acid cycle produces NADH. C) All intermediates of the citric acid cycle have the same number of carbon atoms. D) None of the intermediates of the citric acid cycle are used by other pathways.Question 15: In skeletal muscle cells, the NADH that is produced by glycolysis underanaerobic conditions(vigorous exercise) is regenerated to NAD+by the conversion of: A) acetaldehyde ethanol. B) lactate pyruvate. C) phosphoenolpyruvate pyruvate. D) pyruvate lactate. E) glyceraldehyde-3-phosphate 1,3-bisphosphoglycerate. Page 5 of 7
  6. 6. Chem4412 Winter 2010, Midterm exam #2Name: NetID: .Question 16:The is the site of most gluconeogenesis in mammals. A) liver B) pancreas C) brain D) small intestineQuestion 17:Which molecule cannot be directly transported from the mitochondria to the cytosol? A) acetate B) oxaloacetate C) malate D) phosphoenolpyruvate (PEP)Question 18:The pentose phosphate pathway has two primary products. They are . A) ATP and NADPH B) oxaloacetate and acetyl-CoA C) sorbitol and fructose D) ribose-5-phosphate and NADPH.Question 19: Which enzyme of the TCA cycle does not make use of the cofactor NAD+? A) α-ketoglutarate dehydrogenase B) succinate dehydrogenase C) malate dehydrogenase D) isocitrate dehydrogenase Page 6 of 7
  7. 7. Chem4412 Winter 2010, Midterm exam #2Name: NetID: . E) True/False: (2 points each) # on Statement scantron Catabolic and anabolic pathways are usually the exact reverse of one 20 another. 21 NAD+ collects electrons released in catabolism. 22 Enzymes cannot distinguish between NAD+ and NADP+. 23 ATP contains one phosphoanhydride bond and two phosphodiester bonds. 24 The “fight-or-flight” hormone epinephrine is a peptide hormone. 25 Glucose is the only hexose which can enter the glycolytic pathway. The reaction mechanism of glyceraldehyde-3-phosphate dehydrogenase 26 involves a thiohemiacetal and a thioester intermediate. 27 Aldolase anchors its substrate into the active site by forming a Schiff base. 28 Glucokinase has a higher vmax and a higher Km value than hexokinase. 29 All glycolytic reactions take place in the cytosol. 30 All reactions of gluconeogenesis take place in the cytosol. 31 cAMP is an intracellular second messenger. Muscle glycogen phosphorylase is activated by AMP and inhibited by ATP 32 and Glucose-6-phosphate under normal metabolic conditions. PEP carboxykinase catalyzes the GTP requiring 33 decarboxylation/phosphorylation of oxaloacetate to form PEP and GDP. 34 Pyruvate carboxylase requires a biotin prosthetic group. 35 The TCA cycle provides intermediates for the synthesis of amino acids. Page 7 of 7