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xs96632 - WWW 1 W493 Name ection 1 Last First MI...

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Unformatted text preview: WWW « 1/ W493. Name ______________________________________ ection 1 Last, First MI Instructor: R0 H. Doi < \/ First Midterm .___ , - October 22, 2002 " ’ .., There are 12 pages to this examination including this front page. Please count them to make sure they are all present. Write your name on every page before you start! AG'° = -nFA E'o AG'° = -RTan'eq AG = VAG'°+ RTIn[Products]/[Reactants] E = E'o + RT/nF x ln[Electron Acceptor1/[Electron Donor] Faraday 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. | neither received nor furnished any 'help" during the exam, nor did I use any unauthorized references. Signature ______________________________ I. ,lD# ___________________________ auth—ori—ze tEE—Jn—rCSrER}?SBBBE&§E§tEBEFJfi§ graded exam (e.g. handed out in class or left in a bin for me to pick up). E 0' (V) +0.816 +0.55 +0.29 +0.25 +0.23 +0.07 +0.045 +0.031 -0.185 -0.197 -0.22 -0.30 -0.32 -0.32 -0.41 -0.43 Redox Potentials Electron Acoepto r 02 cyta 3 fumarate pyruvate acetaldehyde FAD FMN NAD+ Redox reaction (1/2 reaction ) 1/20 2+2H++2e' -------- >H 2o cyt a3 (Fe3+) + e- ------- > cyt a 3 (Fe2+) cyt a (Fe3+) + e ' ------- > cyt a (Fe 2+) cyt c (Fe3+) + e ' --------> cyt c (Fe 2+) cyt c1 (Fe3+) + e' ------- > cyt c 1 (Fe2+) cytb(Fe3+)+e' ----- >. cytb(Fe 2+) CoQ + 2H+ + 2e' -------- > CoQH 2 fumarate + 2H+ + 2e ' ----> succinate pyruvate + 2H+ + 2e ' ---> lactate acetaldehyde + 2H+ + 2e ‘ ---> ethanol FAD + 2H+ + 2e ' --------- > FADHZ FMN + 2H+ + 2e ' -------> FMNH 2 NAD“ +H++2e' ------- > NADH NADP+ + H+ + 2e ' ----> NADPH 2“ + + 2e " -----..-------___> H 2 Fd (F63+) + e ' ------------ > Fd (Fe 2+)» Name __________________________________ Last First 1. (30 points) a. (10points) Place a + before each true statement. You will be penalized for wrong answers. __ During glycolysis energy in the form of ATP is derived, and the over-all pathway therefore has a positive AG’° value. j: The steps in glycolysis, where ATP is used to drive the reactions, are carried out by hexokinase and fructose—B-phosphate kinase. i The reactions carried out by hexokinase and fructose—G-phosphate kinase during glycolysis are essentially irreversible. _ The products of aldolase during glycolysis are glyceraldehyde-2-phosphate and dihydroxyacetone phosphate. i The substrate level phosphorylation steps during glycolysis result in the formation of ATP and have negative AG’° values. i Although the aldolase reaction during glycolysis has a large positive AG’° value, it can proceed because glyceraldehyde-3-P is removed quickly by the next reactions. i In the reaction glucose + Pi ----- > glucose-G-P + H20, AG’° = 13.8 kJ/mol. If that reaction is coupled with ATP hydrolysis, the over-all AG’° for the coupled reactions is -16.7 kJ/mol. _ There is a net synthesis of 4 ATPs during glycolysis of one mole of glucose. iDuring glycolysis, the energy to drive the pyruvate kinase reaction is derived from phosphoenolpyruvate. ' Z‘: Under standard conditions (1 M components) fora reaction, when Keq is greater then one, the AG° for the reaction is negative. __ The aldolase reaction during glycolysis has a large positive AG value and is irreversible. i Under standard conditions (1 M components) for a reaction, when AG° is positive, the Keq for the reaction is less than one. “L" NADH formation during glycolysis occurs during oxidation of glyceraldehydes-S-P to 1,3 bisphosphoglycerate. __ NADH formation occurs when acetaldehyde is reduced to ethanol by alcohol dehydrogenase in yeasts. j; NAD+ regeneration occurs in muscle cells when pyruvate is reduced to lactate. ln kinase reactions, the (ac-phosphate of ATP is used to phosphorylate various compounds. b. (10 points) When insufficient oxygen is available for muscle cells, pyruvate is converted to lactate. Draw the over-all reaction that converts pyruvate to lactate. Include cotactors and enzymes, it any. You can use words - structures are not necessary. The AG’° for this reaction is —25.1 kJ/mol. c. (10 points) Calculate the AG for the reaction drawn in part (b), if at equilibrium the lactate is present at 100 mM, NADH at 1 mM, NAD+ at 2 mM, and pyruvate at 10 mM. Show calculations. AG : [AG/0+ RT 134” “Pi; = ~as,loo+(8.%is\(zq8> Wu G095)“ (to) ( I) 7 - 25mm +7964 M .2 ’l7,éé(: j/map M “[757 [Lia/M4 2. (40 points) a. (4 points) Explain in words (in the space provided) how energy is msemed during the reactions carried out by the Willa. EnQ/(gvl is Loosen/ml m NADH (moi Ciao/+35 C04 Last First b. (5 points) Draw the acetylated form of lipoic acid and show how the acetyl-lipoic acid is covalently linked to E2 (dihydrolipoyl transacetylase). Show structure(s). l ‘3 H it” Wz’wz’ Q4» CHuwr CH; Litre/p, (CM; 61“ l l . v , ? 3H LiHlLAC—xe Cfb C10 l CH3 0. (10 points) in the E2 reaction of the pyruvate dehydrogenase complex, the versatile functions of lipoic acid are demonstrated. Describe concisely in words, the various functions of lipoic acid in E2. i (004 UP wG—wH'Cfij on one 3 Gzoop c \\ Q. OxiDlZE‘S (CALOH'CHg) lo _Q«CL¢3 34 Tam/seems AcemL (flaw? To Com To #FOQ/M NET‘IL/COA d. (5 points) Show the functional pant of NAD in its reduced form. Show structure(s). H H Name ________________________________ Last First e. (10 points) What are the main functions of the ih r Ii I h r n (E3) in the pyruvate dehydrogenase (PDH) complex? Answer concisely in space provided. f. (6 points) When one mole of glucose is oxidized to produce two moles of acetyl CoA and two moles of (D2, how many ATPs can be produced from the W that were produced to this point under aerobic conditions. Show rationale for your answer. GxUlCoWSléfi 2 pupa «7 EAT? e W ”\Dya DH i 2 HAD“ “‘7 / [LL ATP 3. (35 points) a. (6 points) The initial reaction of the TCA cycle involvesj€€fl£:.€ei_L____ and OWN/O MEflTE_ ____ which are condensed to form ___QI€£T_E__________. This reaction has a AG’° value that is -OSITIVE (circle one). The energy to drive this reaction forward is derived from hydrolysis of the _:B_\_O__E_§_:9__R___________ bond of ___QEEEY_L:__CQ_{\_§B __________ . Name _______________________________ Last First b. (5 points) During the TCA cycle there are four important steps at which oxidation occurs. Draw in words, complete reactions (reactants, products, enzyme names, co- factors) for any one of these steps. No structures required. my»? m 50H + Ht [50(l‘rR’ATE ”deg + (32. (SorIWM’E DH - * mot H“ ~ OL,KC1 ADA/g“ HAD F09,TW,L‘?OATE SVCC’QVL'CQA 4' Cw)" 0L/l¢é: :9“ Cbl’QLI-a‘4 «\A GAP FA) 1 > FUMAQPJE §UCCUJPWE §UCCICHC ’Dk’\ [JR/9Q“, ki' $713 W DYALOA’CE ‘ MALATE View“; 339‘ t c. (10 points) When W of acetyl-CoA are oxidized by the lQA cycle, how many ATPs or ATP equivalents can be derived from the TCA cycle under aerobic conditions. Show the rationale for your answer. EHADH xq:l7,wxblr\ x§¢3E>ATQa lAfl’lexbx v = 4MP 5 4 Arcs 19M, xv 1-7 4 PADHL )zZ ; 8 Mfg / 4g ATPS d. (5 points) Put a + by correct statements. L the pyruvate dehydrogenase complex is inhibited by ATP, acetyl-CoA, and NADH. _ high energy charge of the cell activates the pyruvate dehydrogenase complex. __ citrate synthase is activated by ATP, an allosteric activator. X— a-ketoglutarate dehydrogenase is inhibited by succinyl-CoA and NADH. _X high energy charge inhibits a-ketoglutarate dehydrogenase ii energy charge of the cell is high, it stimulates ATP generating pathways. J: ADP stimulates isocitrate dehydrogenase. _x citrate is a competitive inhibitor of oxaloacetate for citrate synthase. 7 e. (5 points) It has been shown that in some oxidative reactions in which NAD+ is involved, that the NADH that is formed is in either the A form or the B form , explain briefly in words, how this might occur (hint: aconitase). 1W ?E>u\i’i AWNRMW7 or MAN 11? Enzyme ’ go (>va one Sam 0? (”mil (5 (Po$§\ BL E . f. (4 points) The malate dehydrogenase step in the TCA cycle has a AG’° = 29.7. Explain concisely in the space provided, how this reaction can go forward With such a large positive free energy change. OXACOME'TME',TH£ ?eo©vrT o? MALNE DEHLIDWé—EHMSE lg comm; gallows—so (arm ACETVL- (04 7’0 POM grew, ,Q A Lame uwmue AC7 ear/nou- 50 Tag MMM’E "DR STEP is 304090 ’76 Foul (u Tflfinfiw éo «tie dice (Drama fléé" cm 89 oueawufi, 194/1, ' 4. (40 points) a. (8 points) Draw a common carried out by pyruvate carboxylase that occurs in liver and kidney. No mechanisms required. Show structures of reactants and products and any necessary ancillary (supplementary) factors. You can use abbreviations for co- factors. ’PyaovprTE [4 ”£093: 4 ATP "fig/,9 OAJH A99+iPi QLCm‘L COAGD Name _______________________________ Last First b. (2 points) Why is energy input required for the pyruvate carboxylase reaction? Explain concisely by words 9; structures. TRE “29/05 we? ’ea Com/em?» "r0 CO; 99 FF TA‘iCEg 3mm. use 0? wee/9M mom lXTPo 696%ij TD Mme A “fig, c. (10 points) Animal cells do not have a glyoxylate cycle because they do not have the enzymes _'_W_and ”Mikfifguéi‘lflféfiu. The two acetyl-CoAs incorporated into the glyoxylate cycle are condensed with axééfiééfflf‘i ______ and with __“€_1::LQX,\1_L_E_TE ___________ Ct/lfifl’TE to form #_____________________.__ and _____________________________ . The glyoxylate cycle results in the net synthesis of which can be used in the ”VGA cycle or for the synthesis of glucose. The glyoxylate cycle can be considered a type of AQB_€EEQ_§QI_€: ________ reaction to provide a net amount of éUQ HAVE 0(2- OA A for the TCA cycle. (20 points) The-cleavage of isocitrate in bacteria that have a glyoxylate cycle system can lead to the synthesis of __€Z2LQ_LQ_2(_I_E____~__ and __Q~_L_i7_X_‘/_L§:E or of __t_J_\_: {lg/Oi EQME and _______ C’Q 9:11 _________ depending on the enzyme that cleaves it. The products can lead to the synthesis of either more ATP or more glucose. The regulation of this system is dependent on the Name ______________________________ Last First presence or absence of active isocitrate dehydrogenase (IDH) which can be covalently ATP and IDH kinase, and modified by use of co-factor which results in an ACTIV @ (circle one) form of IDH kinase.. The IDH kinase is active when there I'@ HIGH (circle one) concentration of TCA and glycolytic intermediates. High concentrations of TCA cycle and glycolytic intermediates .ACTIVATE (circle one) the IDH kinase and therefore stimulate ATP synthesis, because the IDH is now.lNACTlVE (circle one). When IDH is inhibited, then the isocitrate is cleaved by the enzyme EQQIEUTC" LVASE; which results in products that favors the synthesis of glucose. 5. (45 points) a. (5 points) When electrons are transferred from the succinic dehydrogenase complex of the electron transport system (ETS) to coenzyme Q, what is the AG'° of the reaction? Show calculations. f AEO 2 o. ovs’ , AGO? / h l: AEID -: '1. (45)®@%§> (”0.12) 5 , St, NE JIM? Aft; : 0'3“; Os; : ,5“ lei/my? b. (5 points) When electrons are transferred from NADH through the NADH dehydrogenase complex (Complex I) of the electron transport system (ETS) to oxygen. what is the efficiency of ATP formation based on the free energy available and the known amount of ATP made by passage of electrons from NADH to oxygen. Show calculations and rationale. argonemg sows/ma 7 4, Gib 9190-95) is o N3 090% (.' I"? (a/VWD: qr“! IO 0’1 ‘ _,~ 5L3 3m 14.1 . 737/03 ” qu) L} Q Q, 416lo> 4/0. .4 - «QM mm 10 Name ________________________________ Last First 0. (5 points) What properties of coenzyme Q make it suitable to transfer electrons from complexes l and ll to complex Ill? ‘6 ®lT is H‘lDQC?V<D%lC sir UDPJLE no THE Meuemm @ 1T CM Mtge? 036 Amp TWO etEc—i’eogg 9&5 DU 0W: a; my ELEC’TRDUES AND a id KWIEL @DlT CW $50198 AS llJ/iEQM€Df4W/li tLE 0’90 yams We El W0 amt) creme/(as. + sign in front of the correct answers only. d. (10 points) For the following statements, put a Base your answers on the discussion given You will be penalized for incorrect answers. in class on the ETS, the mitochondria, and the Mitchell hypothesis. f: The proton motive force during oxidative phosphorylation is developed when protons are moved from the inner membrane to the intermembrane space. d in the inner mitochondrial membrane, __ in the electron transport system foun er membrane space. Complex I, ll and IV are believed to translocate protons to the inn en during oxidative Electrons can be transferred from substrates to oxyg fer, and transfer of hydrogen phosphorylation and metabolism by direct electron trans atoms, but not by transfer of hydride ions. Jf The pH is lower in the intermembrane space than in the matrix during electron transfer. 000 is not able to move through the inner membrane from complexes land ii to complex lll because it has a long hydrophobic isoprenoid side chain. :i If oligomycin is added to the mitochondria, ATP synthesis is inhibited but electron transport can continue. :3; An intact inner mitochondrial membrane is necessary for ATP synthesis according to the Mitchell hypothesis. 1 The level of ADP in the cell influences the rate of respiration and oxidative phosphorylation. __ The charge on the outer surface of the inner membrane is more negative than the charge on the inner surface of the inner membrane during electron transfer by the electron transport system (ETS). The ATP made by ATP synthase is made in the intermembrane space of mitochondria. 11 Name _______________________________ Last First 9. (5 points) During oxidative 'phosphorylation there is an electrochemical gradient. Define what is meant by an electrochemical gradient. ELQWO 6693\‘607 is ’DcMopsTerED 53y A Moat; i905“NE [MW 0") 7W;— OVTFL SiDE or: lDNG/(L MWQQM$ Tum ox} ”Tm; NUBOS‘DE _ Wee Aeg Molar; w (Worms) (1“;wa M Wits/W v Tum id WE 0%in M m Nita; MeMerLAue Sam: f. (5 points) How does‘ dinitrophenol (DNP) disrupt ATP synthesis by the mitochondria? Explain in words. i rd 1} 6L 9UP \S A NEW: MID “WAT 0A.) ”TENQQSE THE MWOC—UOJDQJAL MWBQNJE,» (T W£é®fg (5mg W Maw , Eiggoelmes 2i aeoaaéEs We ©Q®mw$ Mam saggwe W P907790 (Tabla)? g. (5 points) Why is the malate-aspartate shuttle system necessary during oxidation of NADH by the ETS? Explain in words. The éwme five; Racewa— POWELQMDH) in "me (VTD 50L MD 29906428 0M TD MAlATE When Mg mg MALME is "was Owblzeb TD K i H E L/ I S g 33% is mscec, 9p NADH can we a MATQDU h. (5 points) What are the properties of valinomycin that make it an effective uncoupler of oxidative phosphorylation? bewbubei M MATE” .' VALMDm/(m Cmd$©BwD VJ C?) h (m Wyefst rupee “9443””: Lt "mice id im-a WWW IP DMD “ 12 Tu»: ELEC’TKlCBL (omega) (TfifliPieui/ ...
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