xs96753 - Biological Sciences 103 Name Section 1 Last,...

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Unformatted text preview: Biological Sciences 103 Name Section 1 Last, First Ml Instructor: Roy 11. DOi First Midterm October 21, 2003 Be sure to write your name and ID number on the Scantron sheet. There are 11 pages including this front page. Please count to make sure all pages are present. There are 40 questions. Each question has only one best/complete answer. Each question is worth 5 points. Please mark the Scantron sheet carefully with a #2 pencil. Be sure to turn in this exam along with your Scantron sheet. AG'O = -nFAE’0 AG’° = -RT1nK'eq AG = AG’°+ RTln[Products]/[Reactants] E = E'0 + RT/nF x ln[Electron Acceptor]/[Electron Donor] F aradax constant, F = 96,500 J/V/mol Gas'constant, R = 8.315 J/mol K 25°C = 298 K Honor Code: My signature below affirms that I wrote this exam in the spirit of the honor system of UC Davis. I neither received nor furnished any "help" during the exam, nor did I use any unauthorized references. Signature I, , ID# authorize the University to publicly distribute this graded exam (e. g. handed out in class or left in a bin for me to pick up). Eo' (v) +0.816 +0.55 +0.29 +0.25 +0.23 +0.07 +0.045 +0.031 -0.185 -O.197 —O.22 —0.3O -O.32 —O.32 —O.41 -O.43 Redox Potentials Electron Acceptor fumarate pyruvate ace talde hyde FAD FMN NAD+ NADP+ H+ Fd (Fe3+) Redox reaction (1/2 reaction) 1/2 02 + 2H+ + 2e' ———~> H20 cyt a3 (Fe3+) + e- -—-—--> cyt a3 (Fe2+) cyt a (Fe3+) + e‘ ---——~—> cyt a (Fe2+) cyt c (Fe3+) + e’ -——~—-—> cyt c (Fez‘l') cyt c1 (Fe3+) + e’ —-—-—> cyt c1 (Fe2+) cyt b (Fe3+) + e' ———-’—> cyt b (Fe2+) CoQ + 2H+ + 2e' -——-——-> CoQHZ fumarate + 2H+ + 2e' ———> succinate pyruvate + 2H+ + 2e~ -—-> lactate acetaldehyde + 2H+ + 2e' ——> ethanol FAD + 2H+ + 2e‘ ————-—> FADHZ FMN + 2H+.+ 2e' —-——-—-> FMNHZ NAD+ + H+ + 2e“ ——--———> NADH NADP+ + H+ + 2e' -——---> NADPH 2H+ + Ze‘ ——————— --> H2 Fd (Fe3+) + e‘ --—-———-—-—> Fd (Fe2+) 1) Which of the following statements is false: a. The free energy of a reaction is the amount of energy available to do work. n a biochemical process, the energy released. in an endergonic reaction can be used ‘ to drive another reaction that is exergonic. c. The biochemical standard free energy change is a value which takes pH into consideration. (1. Standard free energy changes are additive. e. The first law of thermodynamics states that the total amount of energy in the universe remains constant, although the form of the energy may change. 2) phosphocreatine + H20 —> creatine + phosphate AG" = -42.8 kJ/mol If the concentration of phosphocreatine, creatine and phosphate is 1 mM for each in the cell, what is the AG for the hydrolysis of phosphocreatine? The temperature of the cell is 37° C. a. 418.6 k J/mol b. — 54.5 kJ/mol @606 kJ/mol d. —70 kJ/mol e. -71.6 kJ/mol 3) Which of the following enzymes catalyzes a reaction in glycolysis that is reversible, even though the biochemical standard free energy change for the reaCtion is —18.5 kJ/mole. a. pyruvate kinase b. hexokinase c. phosphofructokinase phosphoglycerate kinase . pyruvate dehydrogenase ’A 4) Substrate level pho’sphorylation is carried out during glycolysis by aghexokinase a, ruvate kinase 1 c. glyceraldehyde-3—phosphate dehydrogenase d. phosphofructokinase e. enolase 5) The enzyme, lactate dehydrogenase, catalyzes a reaction that converts to , which functions to regenerate so that anaerobic glycolysis may continue. a. pyruvate, lactate, NADH b. lactate, pyruvate, NAD+ pyruvate, acetaldehyde, NADH ® pyruvate, lactate,‘NAD+ e. pyruvate, lactate, ATP 6) The following enzymes carry out physiologically irreversible steps in glycolysis: a. hexokinase, phosphofkbctokinase l, aldolase b. hexokinase, phosphoglucerate kinase, pyruvate kinase c. hexokinase, phosphofructokinase 1, phosphoglucerate kinase d. phosphofructokinase 1, phosphoglucerate kinase, pymvate kinase exokinase, phosphofructokinase 1, pyruvate kinase 7) The products of aldolase during glycolysis'are a. glyceraldehyde—3-phosphate and 3 phosphglycerate @ihydroxyacetone phosphate and glyceraldehyde—3-phosphate C. dihydroxyacetone phosphate and phosphoenol pyruvate d. glyceraldehyde—3-phosphate and phosphoenol pyruvate e. pyruvate and phosphoenol pyruvate 8) Sulfur is present in all of the following compounds except: a. biotin, b. lipoic acid @iacin d. thiamine v e. coenzyme A 3’ V 9) The pyruvate dehydrogenase complex converts pyruvate to acetyl-COA. Which of the following is not true: a. Thiamine pyrophosphate is attached to the E1 subunit. b. Before lipoate carries an acetyl group on the E2 subunit, it is present in the oxidized disulfide form. An acetyl group is transferred to CoASH, forming a high energy thioester bond. AD+ is covalently attached to the E3 subunit. e. The pyruvate dehydrogenase complex catalyzes an oxidative decarboxylation with the release of C02. 10) All of the following compounds are derived from vitamins except: a. thiamine pyrophosphate b. biotin ipoic acid . coenzyme A e. flavin adenine dinucleotide ll. Lipoic acid and biotin are co—factors linked covalently to their proteins by forming an bond with the group of a residue present in the protein a. ester, carboxyl, aspartic acid b. phosphate, hydroxyl, serine mide, e—amino, lysine thioester, sulfliydryl, cysteine e. amide, carboxyl, lysine 12) The pyruvate dehydrogenase complex can be inhibited by covalent modification of the El complex " a. when there is an excess of ATP b. when there is an excess of NADH + H+ c. when there is low energy charge . and b. e. a, b., and c. 13) Pantothenic acid is an important component of a. thiamin pyrophosphate b. lipoyl amide" ©oenzyme A d. dihydrolipoyl dehydrogenase e. pyruvate carboxylase 14) The following statements about Coenzyme A (CoASH) are true except for a. It has a terminal sulfliydryl group at its active site. b. E2 of the pyruvate dehydrogenase complex can transacetylate CoASH at its active site. @Hydrolysis of the thioester group in acetyl-COA results in a large positive free energy change. (1. It plays an important role in the initiation of the tricarboxylic acid (TCA) cycle e. It takes part in an aldol condensation reaction with oxaloacetate to form citrate. 15) The conversion of glucose to pyruvate produced ATP. The conversion of glucose to acetyl—CoA produced ATP. The complete oxidation of glucose produced _ ATP. Note: Include the number of ATP equivalents when calculating the total number of ATP produced. 3.10, 3,24 b.10, 6, 32 c. 8, 6, 32 @8, 14, 38 e.6,10, 38 16) Which ofthe following is not true: a. Alpha—ketoglutarate dehydrogenase complex catalyzes an irreversible reaction. b. Oxaloacetate can be used to make aspartate. c. One of the functions of the TCA cycle is to provide carbon skeletons for the synthesis of amino acids. d. The pyruvate dehydrogenase complex and the alpha-ketoglutarate dehydrogenase , complex share the same five cofactors. ’ a V 4 ATPs are formed during one round of the TCA cycle. 17) In the asymmetric reaction carried out by aconitase, one of the following explanations is true. a. there is a three point attachment of the substrate by the enzyme that recognizes either of the ~CH2-COOH groups. b. there is an asymmetric two point attachment of the substrate by the enzyme that recognizes one of the —CH2—COOH group but not the other. @herc is a three point attachment of the substrate by the active site of the enzyme that recognizes one of the —CH2—COOH group but not the other. d. there are four sites of recognition of the substrate by the enzyme that allows hydroxylation of . both of either of the "CHQ-COOH groups. e. there is recognition of the bottom side of the substrate by the enzyme which allows it to make an A or B form of the substrate. 18) During allosteric activation of isocitrate dehydrogenase (IDH) by ADP all but one of the following statements is true. ’ @he ADP is binding to the active site of IDH . ADP and ATP can bind at the same site on IDH c. the binding of ADP causes a conformational change of IDH and decreases its Km for citrate. d. ADP is not sterically inhibiting the binding of isocitrate at the active site. e. the ADP is binding to a site away from the active site of IDH and changing its conformation 19) In the PEP carboxylase reaction found in plants and microorganisms, is a negative effector because it is a of a short pathway, and causes inhibition. On the other hand is a positive effector for the enzyme which tells the TCA system to be more active. a. aspartate, product, competitive, GTP b. glutamate, product, non—competitive, fructose—1,6—bisphosphate c. aspartate, product, feedback, fructose—6—phosphate aspartate, product, feedback, fructose—1,6-bisphosphate e. malate, precursor, competitive, phosphoenolpyruvate 20) The conversion of fluoroacetate to fluorocitrate in the mitochondria is an example of ,r a. covalent modification b. post-translational modification 0. congenital metabolic dysfunction ©netabolic conversion . allosteric modification 21) The following compound releases the most free energy during its hydrolysis: a. acetyl—CoA 2» acetate + CoASH b. ATP => ADP + phosphate ©hosphoenol pyruvate =3 pyruvate + phosphate (1. glucose—6-phosphate => glucose + phosphate 0. 1,3—bisphophoglycerate =: 3 phosphoglycerate + phosphate ts, 22) The conversion of pyruvate to oxaloacetate: s catalyzed by pyruvate carboxylase . requires ATP to activate niacin c. involves biotin condensation with the keto form of pyruvate (1. involves the formation of NADH + PH 6. occurs in both plants and animals 23) Phosphoenolpyruvate reacts with to form the product . This reaction is catalyzed by the enzyme , and is inhibited by a. ATP, pyruvate, PEP carboxykinase, F 1,6—biSphosphate b. Bicarbonate, oxaloacetate, PEP carboxykinase, F 1,6—bisphosphate .; . ‘ TP, oxaloacetate, PEP carboxylase, aspartate, .Bicarbonate, oxaloacetate, PEP carboxylase, aspartate e. ATP, malate, malate synthase, F 1,6—bisphosphate. 24) All of the following statements are true except: a. The glyoxylate cycle occurs in plant seeds. Malate synthase converts glyoxylate and acetyl—COA to succinate. c. Isocitrate lyase is not found in humans. d. The glyoxylate cycle results in the net formation of succinate, and oxaloacetate. e. Citrate synthase converts oxaloacetate and acetyl-CoA to citrate. 25) Oxaloacetate can cross the mitochondrial inner membrane. a. true @alse 26) Malate synthase converts to , which can be converted into a. isocitrate, malate + acetyl—CoA, succinate b. glyoxylate + acetyl-CoA, succinate, aspartate Kbglyoxylate + acetyl-CoA, succinate, protein @lyoxylate + acetyl—CoA, malate, glucose e. citrate, malate, glucose 27) Animals lack the following enzymes a. fumarase, pyruvate kinase, pyruvic carboxylase . isocitrate dehyrogenase and malate dehydrogenase 'socitrate lyase, malate synthase, PEP carboxylase . malate synthase, malate dehydrogenase, aldolase e. ATP synthase, cytochrome oxidase, succinic dehydrogenasc 28) All of the following are located in the mitochondrial matrix except: a. pyruvate dehydrogenase complex b. succinate dehydrogenase ,; fumarase \@ nolase e. citrate synthase 29) The following statements about the glyoxylate cycle are true except for a. two acetylyl—CoAs are converted to produce a net amount of succinate. ocitrate is cleaved by isocitrate dehydrogenase c. glyoxylate is condensed with acetyl-COA to form malate d. one mol of NADH + H+ is produced during one round ofthe cycle. e. the concentration of TCA intermediates influences whether isocitrate is utilized for the TCA cycle or the glyoxylate cycle. 30) The function of the glyoxysome in plants is important because a. it fills up the TCA cycle by using acetyl-CoAs to make succinate which is transferred to the mitochondria. b. it makes malate which can be converted by several steps to glucose prior to the synthesis of carbohydrates by photosynthesis. c. it allows the synthesis of both glucose and ATP (in the form of NADH) d. a. and b. @1, b. and c. 31) When electrons are transferred from NADH to cytc, the following amount of free energy is released. a. —l3.5 kJ/mol b. ~55 kJ/mol c. —6l.8 kJ/moll 10 kJ/mol e. —l30 kJ/mol 32) The following statements are true about ubiquinone (COQ) except for a. it is a hydrophobic co-factor with a long side—chain b. it can accept electrons one at a time in sequence c. it is mobile in the inner membrane of the mitochondria @t has a more negative redox potential than NADH e. it can transfer one electron at a time to cytochromes in complex III 33) When FADH2 sends its electrons through the electron transport system to oxygen, 2 ATPs were formed. What is the % efficiency of this electron transport pathway to make ATP? a. 10% b. 20.5% @0.5% d. 45% e. 555% 34) . According to the Mitchell hypothesis, during oxidative phosphorylation the following are required except for * a. a supply of electrons through the electron transport system. n intact outer mitochondrial membrane \a c. ADP, phosphate, and 02 d_ an electrochemical gradient and active ATP synthase system c. an intact inner mitochondrial membrane 35) According to the Mitchell hypothesis, ATP is synthesized when are passed through the core of and this provides the energy to synthesize ATP from ADP and phosphate by a. ADP, ATP synthase, F0 b. protons, ATP synthase, F0 c. electrons, ATP synthase, Fl ©protons, ATP synthase, F1 6. electrons, ATP synthase, F0 36) Dinitrophenol can uncouple electron transport from oxidative phosphorylation because it is a weak acid, it can diffuse readily across the r mitochondria membrane, and dissipate the gradient. a. hydrophilic, outer, proton b. hydrophobic, outer, proton c. hydrophilic, inner, electrical @ydrophobic, inner, proton e. hydrophilic, inner, proton 37) Because valinomycin + KJr is soluble, it crosses the inner mitochondrial membrane _ thereby the membrane potential. As a result, the proton gradient is a. Water, increasing, unchanged. b. Water, decreasing, unchanged 0. Water, decreasing, changed. (1. Lipid, increasing, changed Lipid, decreasing, unchanged. 38) Proton Motive Force provides energy for ATP synthesis, adenine nucleotide translocase and phosphate translocase. (a . false 10 39) Which of the following is not true: a. Ubiquinone can readily move through the mitochondrial inner membrane. @Complexes 1, II and 111 function as proton pumps that contribute to the proton motive force. c. Rotenone inhibits the electron transport system at complex I. d. The proton motive force is made up of an electrical and chemical gradient. e. One of the requirements for oxidative phosphorylation is an active ATP synthase. 40) During electron transport in the electron transport system of the mitochondria, the following statements are true except for a. the outer side of the inner membrane is positively charged. b. the pH of the matrix is more basic than the pH of the inner membrane space. c. protons are extruded into the inner membrane space. @he pH of the inner membrane space is more basic than the pH of the matrix. e. the inner side of the inner membrane is negatively charged. ll ...
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xs96753 - Biological Sciences 103 Name Section 1 Last,...

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