midterm1 Spring_2001

midterm1 Spring_2001 - ti\ Hun-t Metabolic Biochemistry J'...

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Unformatted text preview: ti\ Hun-t Metabolic Biochemistry J' BIEC 11312 First Exam i 1. Fill in all eut'the enzyme catfltjr'zed. reeetiens en the lewer right. Draw the comet structure abbreviation: of any other reactants and [meme-tie gmupi ieg. bietin. T'F'P. ete.}t. {A} Glu ease .—.._...._.._.._._.-_-..—I ---- -.-.——u.-- [E] Shut-t the path ef 14C lithe carbon 5. Spring Hill] which cent-en the substratesls} en the upper left to the pmduetiej fer eae‘tt intermediate meleeule. Include the names or products [eg, ATP. ADP. Pi. NAIR MADE-t, ete}. and any required Ethanol _..._....._-——-_u.--—.——n---...—u--_—-—I- —,_u-——.-.—----_-.-.—u--—-—- | in eaeli meteeule abeve starting with glueuse teheled in 1E1. When oxygen is comotred from a suspension of yeast cells using glucose for energy, the rate of glucose consumption increases dramatically and ethanol begins to accumulate in the media. This effect, first obscured by Pasteur. is characteristic ofmoet cells capable of both aerobic and anaerobic mill-nation of glucose. A. Why did ethanol begin to accumulate when oxygen was removed ‘? B. Assuming the ATP needs ot‘the cell are oonotanl, what will he the relative increase in glucose concomption'.’ In order to receive crec'llt1 you must show your calculations. (2, What mgulfllflfi' mechanisms explain how the remove] ol'oxygen increases the rate of glucooe ounsumptifln'? Explain in terms ofaoccilic cnxyenee. D. What effect does the removal of oxygen have on the rate of C02 generation? 33' what factor does the rate ofCOE generation change? Show your calculations. W. {A} In the epaee below please sketch the v versus 5 plot for an enzyme eheying Mieheelie—Menten “I kinetiee, and indicate on this graph Km and Vertex. {B j [n the space helew, please sketch the v vemue S plot for an enzyme which ehewe pescitive eehpemtlvtty :in substrahe binding, in the presence and sheath: ef :ttt elieeten‘e in hihiter. {C} In the above graph, please indicate whether the alteeterie inhibiter increase-e at Ciel-1mm the apparent Km the this reaction. What Fen-n hf'the allneterie enzyme binds the inhibitor better, the E. state or the T slate? {D}. Chmidur the reaction: ATP + pymyete —r pheepheenel pyruvate + ADP Given that the .fitfi'“ for ATP hydrolysis {e —3E|.5 Ht'mei, the at “" Fur phfiiphflenfllpymvatv hydmlysie is 41.9 kjnuhl, HT is 1.118 kJIm-u], and 1he eetbeentmtien are: {ATP} = 2.14 mi'vl. {ADP} = Ulimh‘l, tyymvete} = QGSJmM. {pheepheettelpyruyete} = fl.fl23rnM. and {phnephatejl = 8111M. what will the 513' be For this reeetien? De net calculate an answer. Full credit well] be given fur eerreet set up of the final eqv etiun. 3.13“ = f w W. Multiple Choice. Choose only one answer for each question. I. Which one of the following statements is most lztletentlltr false? {A} At steady state in a typical call, all reactions in glycolysis which are not under allostcric regulation have an actual free energy change th'} ofapproitiniately zero. {B} Adenylatt: Itinase catalyzes the reaction: leF + let'f'i’ 2 ADP {C} The rate of an ATP-utilizing hiosynthetic pathway will be increased by a higher; {hTFJliADPltPi} ratio. {D} For the phosphofructoltinase reaction in giycolysis, the ratio of the products tfmctose-l , I5- hisphoephate and ADF; numerator} to the reactants tfmctose-d-phoephate and ATP; denominatorl is sinalleg than jE'IJ-ie reaction were at equilibrium. {E} Under steady state conditions in a typical cell, dis ability of‘stTP hydrolysis to do useful wort; (cg, drive hlosynthetic reactions} is given by the standard Free energy ofATP' hydrolysis. ht?“ - -3tl.5 lei-“tool. not by AG“. 2. In tees. Harden and Young, two English chemists. studied The fermentation of glucose using cell-free extracts of yeast. They ntonltored the conversion of glucose to ethanol by measuring the evolution of carbon dioxide fl'Dl‘tt the reaction vessel. In one set of experiments, Harden and Young observed the evolution slim: and the buildup of forctose-I .ti-hisphocphate when inorganic phosphate [le was added to a yeast attract containing glucose. in the graph. curve A shows what happens when no Pi is added. Curie B shows the effect of adding Pi lit a separate experiment. sits the evolution of CG: a sin a, g, .g' slows with time, more P.- is added to stimulate the reactions; mement- _ this is shown lay curve C. ‘t'tiltich o_|1e of the following fiiflfigflflhmmdw slattments is 1%: Eur-leer: m1 sun’s to} The addition or arsenate to Iiie shove reaction mixture will increase the build up of fructose-l . 5- hisphosphore. {B} The ratio of F; consumed to CD; evolved in curve C will be ELS. {C} The evolution oi'CClg eventually ceases following die addition of P'. because F; is required For the glyceraldehyde dehydrogenase reaction. {D} The addition ofalsettalc to the above reaction mixture will inhibit the fonnation ofelhehol. {E} Glucose fermentation is depend: upon F5 because Pi is required in the glycogen phosphorylase reaction. 3. 1t‘lu’hich one ofthe Following stattrnenls is blatantly ME? [at] The sohsu-ate tier the first enzymatic reaction in the pentosc phoSpltote pathway is glucose-e-P. tEt) Under aerobic conditions. the fate of electron pairs in NADH is to reduce {lg to H20 with the production oi‘ ATP. while the fate of electron pairs in NADE'H is to reduce bonds in hiosynthetie reactions. [Cl The steeds.r state HADPHI'NADP ratio is for larger titan the steady state NADHINAD’“ ratio in cells. {D} The two dehydrogenose steps in the pentose phosphate poutway transfer electron pairs to MADE but not to NAD+ [El The function of the non-osidetive branch of the penrose phosphate pathway is to return the carbons e!‘ the 5 carbon sttgor silenced-P to inteouediates in the citric acid cycle. Which one of the following statements is blatantly false? {A} Phosphol'ructioltinssel is aiiosten'catly egtiyated by rille and by ATP. {Bi Pyruvate dehydrogenase is ellosterieally germ by AMP. {Cl Pswvate deliydregenase horses is attesterieslly mhibjgedby NitDH. {D} Pyntvate dehydrogenuse itinase phosphoeylates and thereby inactivates pyruvate dehydrogenase. [Ell Sinee the reaction catalyzed by pyrovate dehydrogetase is irreversible under physiological conditions. the acetyl Cost product cannot be converted back to pynivate, Which one oFthe Following statemean is blatantly false? {All The prosdietic group for the pyruvate dehydrogenase subunit {- Hg} is dries-nine pyrophosphate. {El} lipoic acid is covalently attached to the E2 subunit of pyntvate dehydrogenase. {E} The prosthetic group for E3 in pyruvate dehydrogenase is FAD. {D} In the pynivate carbonylase reaction. biotin is first carbonylated by Ct]; and then the carbony group of carbosyhiotin is transferred to gyros-ate in a subsequent reaeuim which is driven by the coupled hydrolysis oi'ATP. [Eli The order in which substrates are used in the pyruvate dehydrogenase mechanism is pyruvate, then Cont—SH. then MADE. 1iWhich one oi‘the following statements is blatantly false? n. Lactate dehydrogenase are found in the eytosol, not inside the mitochondria. 13. it is impossible to obtain a net synthesis of oxaloecetate using only the enzymes of the TCA cycle, without depleting the intermediates oi'the cycle. C. Fyruvate carbosyiasc is aliostericaily activated by 11ch Con. El. Cit meditate it the enzyme bound intermediate in the step which converts isocitretc to n- hetogiutarate. Under physiological conditions. the rate of citrate fonuatintt by citrate synthase is detennineei by the concentration of aoetyl Cod; and osoioacetate. P'- 1which one of the following statements is blatantly raise? in] Allosteric regulation oi‘eneyme activity requires that there be at least m additional site, distant from the active site. to which an ailesrei-ie effector can bind. {B} lion ellestcn'e ligand binds to the it state, the enzyme will be M catalytieaiiy active. {C3 The aerit-atien of glycogen phosphorylase by the phosphofllation of a specific serine residue in sigh of its subunits is an example of covalent regulation. {D} Phosphoi'nietoltinase must have two. binding sites for ATP. the active site and an allesrci-ic. site. (E) The sufitme for glycogen phosphorylase phosphatase is the "b" {or less active} form of glycogen phospharyiase A cell extract containing all of the enzymes of glyuelysis is incubated with 3JP labeled ATP {i.e., Adenosine - P - F - 32 P} and glucose. dissonung that inorganic phosphate is unlabeled, which of the Foliowing labeled compounds would be tanned? iii Glucosewb-E'EP {3} Wilmette i-33i’. d-jzll-bisphosphalu (I) 2-31P phosphoenol pynavate [4]: I P1 3-33P—Bisphosphoflyoetate in] land} {B} 1.2.and3 {C} Ilandti [D] 4 {E} Allofthe above Which one of the following statements is blatantly false“? {M The net eTI’ equivalents produced per glucose Subunit oi‘ glycogen in an anaerobic muscle cell is 3. {B} The net ATP equivaiems produced by substrate level phosphorylation in the complete aerobic eatubolism ofglucose to 6CD; is Ii per glucose. {CJ The net ATP equivalents produced in the complete aerobic cambolism of glucose in a muscle cell is Hit. {It} The net ATP equivalents produced from glucose in an anaerobic liver cell treated with arsenate is one. (E) The complete estabol'tsm of lactate to 3 Ct): produces 5 Martin: and 1 rating l a H II}. Which uf the fDIJfltl-‘ing reactions weutd be expected to proceed in the direction Shawn under standard eunditiens, assuming that the appmpriate enzymes are present to eamiyze them? {a} Pymvate + NMJH 4- H" —> Iaetate + HAD-— {h} Aceteaeetate + NADI-l + 1-? —t~ fi-hydmxyhutyrate + NARI” (4:) Millet: + NAD“ —r exaleaeetete + NADH + H+ Lit} Pyruvute + Ji-hydrexybuwtate —'.~ lactate + unetuaectate {e} Malate + pymrate —> muieacetate + Lactate {Mast-tad [Biaandb {C} 13311er {D} hande- {E} esttde l L You wilt find below several WNW-fly drawn structures flfin‘lperlzml compounds in biochemistry. Which et' Ihe Tullewt'ltg Ls not represented amour-g these structures? {A} Fifi-DH; {Bl NADPH {CJ thiamine pytephusphute {D} Fructose (E) Biotin H EH1- ? S figfih 1:" p. t" we: I M H a: in a. 41 J11 H5! W :‘1' in: 1'0 5 tag.- f 1 O emf—a- fifli- 1" I in an a; a 'f' a. | “E: W“- on. ermine 1- 65 C} :3" I % me, flakes-95 h a“. fiflfllna a u 4:11 :1 II it!" Ha IR 45'"; Ht ,H a”? W O . NIETABDLI’C BIOCHEMISTRY FIRST EKfiM SPRING 2001 MULTIPLE CHDICE KEY ...
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midterm1 Spring_2001 - ti\ Hun-t Metabolic Biochemistry J'...

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