CH395 G Exam 2 Multiple Choice - Fall 2004 1. Which of the following fatty acids has the lowest melting point? a. Fatty acids with sites of unsaturation with cis double bonds b. Fatty acids with sites of unsaturation with trans double bonds c. Fatty acids with no sites of unsaturation d. Fatty acids with longer hydrophobic tails e. None of these will make a difference 2. What is the major lipid component of biological membranes? a. triacylglycerols b. phosphoglycerides c. fatty acids d. cholesterol e. waxes 3. A membrane is impermeable to charged molecules and does not allow passage of ions because of: a. the thickness of the membrane b. the hydrophobic nature of the membrane c. the hydrophilic nature of the membrane d. all of the above e. none of the above 4. The carbohydrate portion of a glycoprotein is found: a. on the interior side of the cell membrane b. spanning the cell membrane c. on the exterior side of the cell membrane d. all of the above e. none of the above 5. Which of the following is not a specific advantage of enzymes? a. Enzymes can be quickly “turned off” by allosteric control. b. Enzymes can function at large ranges of pH and temperature. c. Enzymes exhibit very high substrate specificity. d. Enzymes can catalyze reactions several orders of magnitude faster than chemically-catalyzed reactions. e. Enzyme activity can be enhanced through covalent modifications.6. Which of the following statements about cofactors/coenzymes is not true? a. Many vitamins serve as coenzyme precursors. b. Metal ions could serve as cofactors. c. NADH is a coenzyme that catalyzes redox reactions. d. Coenzymes can be either transiently or permanently associated with an enzyme. e. Once a coenzyme is chemically changed in a reaction, it must be regenerated by the same enzyme. 7. Which of the following equations accurately describes enzyme-catalyzed conversion of substrate to product? a. E + S → ES → E + P b. E + S → ESP → E + P c. E + S → EP → E + P d. E + P → E + S e. none of the above 8. What is an accurate velocity equation for the following reaction if [B] is in excess? A + B → C a. v = -d[A] b. v = -d[B] dt dt c. v = -d[C] d. v = d[A] dt dt e. v = d[B] dt 9. Competitive inhibitors have the following effects on KM and Vmax: a. They alter the value of KM but not Vmaxb. They alter the value of Vmax but not KMc. They alter the value of KM and Vmaxd. none of the above e. all of the above 10. Mixed inhibitors have the following effects on KM and Vmax: a. They alter the value of KM but not Vmaxb. They alter the value of Vmax but not KMc. They alter the value of KM and Vmaxd. none of the above e. all of the above11. A system at its transition state a. is at its lowest free energy value. b. requires a large amount of energy to proceed to product. c. has an equal probability of proceeding to product or decomposing back to reactants if ∆Greaction = 0. d. describes a system in which the reactants have not yet come into contact with one another. e. describes a system in which products have been produced. 12. One way in that an enzyme can carry out the catalysis of a reaction is by a. preferentially binding the transition state analog of a reaction. b. carrying out redox reactions. c. bringing substrates close to one another. d. aligning substrates in the proper orientation for a reaction. e. all of the above. 13. In gluconeogenesis, the initial reaction converts pyruvate to a. oxaloacetate b. acetyl-CoA c. phosphoenolpyruvate d. lactate e. malate 14. The enzyme in gluconeogenesis that reverses the reaction of phosphofructokinase in glycolysis is a. glucose-6-phosphatase. b. fructose-1,6-bisphosphatase. c. pyruvate carboxylase. d. hexokinase. e. none of the above 15. If a reaction has a negative ∆H value and a negative ∆S value, it is a. spontaneous at all temperatures. b. unspontaneous at all temperatures. c. spontaneous at high temperatures and unspontaneous at low temperatures. d. unspontaneous at high temperatures and spontaneous at low temperatures. e. none of these are correct. 16. The conversion of dihydroxyacetone phosphate to give glyceraldehydes-3-phosphate is a(n) a. phosphorylation b. cleavage c. phosphate transfer d. isomerization e. dehydration17. Glucose residues are cleaved from a glycogen branch until is about three units long. What enzyme is required to continue glycogen breakdown? a. debranching enzyme b. branching enzyme c. glycogen phosphorylase d. glycogen synthase e. phosphoglucomutase 18. In glycogen synthesis, what happens when UTP concentrations get low? a. UTP levels have no effect on glycogen synthesis. b. Glycogen synthesis stops. c. ATP is used instead of UTP. d. ATP replenishes UTP supply through nucleoside diphosphate kinase. e. Another branch point is formed and synthesis continues from there. 19. Pyruvate carboxylase a. is located in the cytosol. b. has acetyl-CoA as a negative allosteric effector. c. uses biotin as a coenzyme. d. converts pyruvate to malate. e. None of these are true. 20. Which of the following is not an activator of PFK? a. ADP b. cAMP c. F2,6BP d. F1,6BP e. citrateCH395G Exam 2 - Fall 2004 1. Small lipid vesicles that are designed to contain drugs or other water-soluble molecules for targeted delivery are called ___________________. liposomes / micelles In animal and plant tissues the energy storage oils and fats are typically _______________________. triacylglycerides / triglycerides / triacylglycerols A type of lipid found in bilayers that is a precursor to steroid hormones is _______________________. cholesterol In fatty acids found in bilayers, the double bond is typically in the _____________ configuration. (+1/2 point for each fill-in-the-blank answer) cis One method of lysing (breaking open) bacterial cells involves the use of the enzyme lysozyme. a) What does the lysozyme do to allow it to break open bacteria? (+1) The cell walls of bacteria are made up of a mesh network containing polysaccharides with alternating NAG-NAM units. Lysozyme cleaves the β(1-4) linkage between the