Biochemistry: Amino Acids, Proteins, and Enzymes - Prof. Steven Van Doren, Exams of Biochemistry

Download Biochemistry: Amino Acids, Proteins, and Enzymes - Prof. Steven Van Doren and more Exams Biochemistry in PDF only on Docsity! BIOCHM 3630 Exam 1 February 7, 2023 1 BLUE Multiple Choice Indicate the answer choice that best completes the statement or answers the question. Amino acid drawings and the Henderson-Hasselbalch equation are given on the last 3 pages. 1. Which of the following is NOT a Functional Group a. Amino group b. Protein c. Alcohol group d. Carbonyl group 2. Which of the following functional groups is specific to an alcohol? a. -NH b. -OH c. -C=O d. C=C e. O-P 3. Biological catalysts are a. proteins exclusively b. RNA exclusively c. DNA exclusively d. some proteins and some RNA 4. Which cell component is able to capture the energy of light? a. Nucleus b. Lysosome c. Rough Endoplasmic Reticulum d. Chloroplast e. Mitochondrion 5. Prokaryotic cells a. do not have a well defined nucleus b. are smaller than eukaryotic cells c. do not have internal membranes d. all of the above 6. According to thermodynamics, favored processes are a. ones that require energy. b. ones that release energy. c. oxidations. d. reductions. 7. Identify the class of basic biomolecules represented by the following structure. a. Carbohydrates b. Amino acids c. Nucleotides d. Lipids 8. If atoms with greatly differing electronegativities form a bond, that bond will be a. polar. b. nonpolar. c. amphipathic. d. acidic. 9. Many of the properties of water can be accounted for by the fact that a. it is polar b. it forms hydrogen bonds c. it is a bent molecule d. all of these are true 10. Which of the following elements has the highest electronegativity? a. C b. H c. N d. O e. P 11. The water molecule is polar because: a. Electrons are not distributed symmetrically in the molecule. b. The hydrogen atoms are found on one "side" of the molecule. c. Hydrogen is less electronegative than oxygen. d. The hydrogen atoms are found on one "side" of the molecule. Hydrogen is less electronegative than oxygen. e. All of these are correct. 12. Molecules which contain both polar and nonpolar regions are: a. Contain hydrophobic groups b. Contain hydrophilic groups c. Able to form micelles d. Are amphipathic e. All of these 13. Which of the following characteristics makes for a good hydrogen bond acceptor? a. a high electronegativity b. a nonbonding pair of electrons d. SER e. HIS 29. The sequence of monomers in any polymer is this type of structure: a. primary structure b. secondary structure c. tertiary structure d. quaternary structure e. All of these 30. The overall folding of a single protein subunit is called: a. primary structure b. secondary structure c. tertiary structure d. quaternary structure e. All of these 31. Covalent bonds are important in all these structures, except: a. primary structure b. secondary structure c. tertiary structure d. quaternary structure e. All of these 32. What happens when a protein is denatured? a. Its secondary structure is disrupted but its primary structure remains intact. b. Its primary structure is disrupted but its secondary structure remains intact. c. It is broken apart into its constituent amino acids. d. It becomes all α-helix. 33. In the β-pleated sheet conformation a. there are hydrogen bonds perpendicular to the direction of the polypeptide chain. b. the polypeptide chain is almost fully extended. c. the polypeptide chains may be hydrogen bonded together in a parallel or antiparallel orientation. d. all of these 34. Which of the following is the most common function for fibrous proteins? a. enzymes b. structural roles. c. carrier molecules. d. enzymes and carrier molecules. e. All of these. 35. Which of the following is true about the alpha helix? a. the structure is stabilized by hydrogen bonds b. there are 3.6 residues for every turn of the helix c. the sidechains radiate outward d. all of the choices 36. Which of the following amino acid residues would most likely be found in the interior of a globular protein? a. glutamic acid b. lysine c. leucine d. serine 37. The tertiary structure of a protein is usually a result of which of the following interactions? a. intramolecular hydrogen bonding b. electrostatic interactions c. hydrophobic interactions d. all of these 38. Which of the following can result in protein denaturation? a. heat b. extremes of pH c. detergents d. all of the above 39. Which of the following statements regarding hemoglobin (Hb) and myoglobin (Mb) is true? a. Mb transports oxygen while Hb stores it. b. Mb has quaternary structure but Hb does not. c. Mb displays simple kinetics of binding while Hb displays cooperativity. d. Mb binds Fe(II) while Hb binds heme. 40. In the Bohr effect the binding of oxygen to hemoglobin a. is increased by the presence of Na+ b. is increased by the presence of H+ and CO2 that bind hemoglobin c. is decreased by the presence of H+ and CO2 that bind hemoglobin d. is unchanged 41. Which of the following diseases is based on abnormal protein folding? a. Alzheimers disease b. Mad Cow Disease c. Prion diseases d. Frontotemporal dementia e. All of the choices 42. Enzymatic activity has an optimum temperature because a. the component amino acids have varying melting points b. the rate of reactions is thermodynamically controlled c. the side chains of essential residues are chemically degraded at higher temperatures d. raising the temperature speeds up the reaction until protein denaturation sets in e. the organism dies beyond a certain temperature 43. What effect does a catalyst have on the ΔG° of a reaction? a. A catalyst lowers the ΔG°. b. A catalyst raises the ΔG°. c. A catalyst has no effect on the ΔG°. d. It depends on the specific catalyst. 44. A rate constant is a. the rate of a reaction at standard temperature and pressure. b. the rate of a reaction at equilibrium. c. a proportionality constant relating the rate of a reaction to the concentration(s) of the reactant(s). d. a kind of transition state. 45. The active site of an enzyme a. is frequently located in a cleft in the enzyme. b. is the portion of the enzyme to which the substrate binds. c. contains the reactive groups that catalyze the reaction. d. all of these are correct 46. Which of the following is true? a. The E-S complex often dissociates with no reaction taking place. b. The E-S complex must form before a reaction can take place c. Once the E-S complex forms, it can go on to form product or dissociate to E + S d. All of these are correct 47. Which of the following is true about the enzyme chymotrypsin? a. The enzyme can cleave peptides. b. The enzyme can cleave esters. c. The enzyme prefers to cut next to an aromatic group. d. The enzyme can cleave substrates which are not naturally occurring. e. All of these are correct 48. In the reaction catalyzed by chymotrypsin, a graph in which the rate is plotted against the concentration of substrate a. is sigmoidal, characteristic of an allosteric enzyme b. shows that cooperative kinetics are observed c. shows that the reaction is zero order d. is hyperbolic, characteristic of a nonallosteric enzyme 49. In the reaction catalyzed by aspartate transcarbamoylase, a graph in which the rate is plotted against the concentration of substrate a. is sigmoidal, characteristic of an allosteric enzyme b. shows that noncooperative kinetics are observed c. shows that the reaction is zero order d. is hyperbolic, characteristic of a nonallosteric enzyme 50. Which of the following are related for a given enzyme? a. Vmax, KM, and percentage of α-helix b. Vmax, kcat, and percentage of β-sheet d. serine, histidine, aspartate. 65. Which of the following amino acid side chains would best serve as a general acid, assuming the protein functions at a pH of 7? a. alanine b. aspartic acid c. lysine d. asparagine 66. Which of the following statements about coenzymes is true? a. They are commonly derived from vitamins. b. They bind to the active site region on specific types of enzymes. c. They can be metal ions, such as Zn(II). d. NAD+, FAD and biotin are all examples of coenzymes. e. All of these statements are true. 67. The pH buffering reaction of H2PO4 - ----> HPO4 2- has a pKa of 7.20. When the ratio of H2PO4 - to HPO4 2- in a solution is ~1 to 10, the pH of the solution would be . a. 5.20 b. 6.20 c. 7.20 d. 8.20 e. 9.20 68. Four solutions have [H+] concentrations of 1 X 10-3 M, 1 X 10-4 M, 3.2 X 10-5 M, and 1 X 10-6 M, respectively. What are their pH values in the same order as above? a. pH -3, pH -4, pH -3.2, and pH -5 b. pH3, pH 4, pH 3.5, and pH 5 c. pH3, pH 4, pH 4.5, and pH 6 d. pH3, pH 4, pH 5.5, and pH 5 e. pH3, pH 4, pH 5.5, and pH 6 Exhibit 2B Contains information on the pK's of some common buffers. Buffer pK1 pK2 pK3 Acetate 4.75 Ammonia 9.25 Carbonic acid 6.37 10.20 Citric acid 3.09 4.75 5.41 Formic Acid 3.75 Phosphoric acid 2.14 7.20 12.4 Pyruvic acid 2.50 Tris 8.3 69. Refer to Exhibit 2B. The enzyme lysozyme has an optimum pH close to 5. A suitable buffer would be: a. Acetate b. Carbonate c. Phosphate d. Pyruvate e. None of these is a suitable buffer for this reaction. 70. Refer to Exhibit 2B. A phosphate buffer would work well at this pH: a. 5.0 b. 7.0 c. 8.0 d. 10.0 e. 7.0 and 8.0 71. The net charge on the peptide Cys-Ala-Lys-Glu in a solution at pH 7 is closest to a. −2 b. −1. c. 0. d. +1. Exhibit 3B A titration curve. 72. Refer to Exhibit 3B. Which point most likely represents the pK for the carboxyl group? a. 1 b. 2 c. 3 d. 4 e. 5 73. Hydrogen bonds are most important in this type of structure in proteins: a. primary structure b. secondary structure c. tertiary structure d. quaternary structure e. All of these 74. Please find Arginine, which is pictured by letter _____?_____. a. i b. e c. f d. g e. s 75. ? is the nonchiral amino acid pictured that is an example of a NET uncharged, amino acid at pH 7. a. f b. h c. i d. j e. q 76. One of the amino acids depicted below is a branched chain amino acid useful in promoting muscle building. Please find Isoleucine, which is pictured by letter _____?_____. a. k b. p c. t d. s e. None of the above are branched chain amino acids. 77. Please find Asparagine, which is pictured by letter ___?___. a. b b. c c. d d. f e. h 78. Please find Serine, which is pictured by letter _____?_____. a. k b. l c. m d. n e. t 79. Please find Aspartic Acid, which is pictured by letter _____?_____. a. a b. b c. c d. d e. i