Biochemistry Exam Review, Exams of Nursing

Download Biochemistry Exam Review and more Exams Nursing in PDF only on Docsity! BCH FINAL EXAM C - correct answer ✔✔Which of the following curves shows the appropriate relationship between [ES] and time in steady state kinetics? (see graphs on #1) A - correct answer ✔✔Which of the following would represent the reaction coordinate for a two-step reaction with an initial slow step? (see graphs on #2) B - correct answer ✔✔Which of the following amino acids could bind to the specificity pocket of Trypsin? A) Gly B) Lys C) Asp D) Gln E) Val D - correct answer ✔✔The chymotrypsin/trypsin family of proteases has which combination of amino acids in the active site A) threonine, histidine, aspartic acid B) serine, arginine, glutamic acid C) serine, histidine, glutamic acid D) serine, histidine, aspartic acid E) threonine, histidine, aspartic acid E - correct answer ✔✔Which of the following would be a proper representation of enzyme velocity? A) v = (-) d[P]/dt B) v = (+) d[P]/dt C) v = (-) d[S]/dt D) v = (+) d[S]/dt E) Either B or C C - correct answer ✔✔The rate constant associated with the reaction below would be 2A --> B A) Zero order B) First order C) Second order D) Third order A - correct answer ✔✔Which type of secondary structure present in integral membrane proteins is readily detectable in the primary structure? A) membrane-spanning α helix B) membrane-spanning β sheet C - correct answer ✔✔Which of the following lipid types are not found in animal membranes? A) phosphoglycerides B) cholesterol C) triacylglycerols D) glycolipids E) sphingolipids C - correct answer ✔✔A molecule moves across a membrane from a lower to a higher concentration with the aid of a membrane protein. This process is known as: A) chemiosmotic coupling B) diffusion C) active transport D) facilitated transport E - correct answer ✔✔Which of the following will cause the opening or closing of a gated ion channel? B - correct answer ✔✔A patient suffers from premature zymogen activation, so that the pancreatic enzymes are activated in the pancreas rather than the small intestine -- causing damage to the pancreas. Which of the following would be the most effective in preventing these effects? A) chymotrypsin inhibitor B) trypsin inhibitor C) elastase inhibitor C - correct answer ✔✔Which of the following is FALSE regarding transition state stabilization? A) An enzymatic catalyst makes formation of the transition state more favorable. B) An enzymatic catalyst lowers the energy of the transition state. C) Transition state stabilization refers to the shift in the equilibrium of the reaction. D) Enzyme cofactors are often used to stabilize transition state molecules. E) Stabilization of the transition state results in a greater reaction velocity. E - correct answer ✔✔A pH/rate curve with an inflection point at pH~4 suggests the involvement of a(n) ________ in the catalytic step. A) redox cofactor B) basic amino acid C) metal ion D) hydrophobic amino acid E) acidic amino acid B - correct answer ✔✔Glucose is added to cells and the rate of glucose transport is plotted against glucose concentration. In the presence of the galactose derivative 6-O-benzyl-D-galactose the curve is shifted to the right (with no other change). What kind of agent is this galactose derivative? A) Activator B) Competitive inhibitor C) Noncompetitive inhibitor D) Mixed inhibitor E) None of the above D - correct answer ✔✔Which of the following statements about allosteric control of enzymatic activity is false? A) Allosteric effectors give rise to sigmoidal V0 vs. [S] kinetic plots. B) Allosteric enzymes are usually multi-subunit complexes. C) An effector may either inhibit or activate an enzyme. D) Binding of the effector to the active site changes the conformation of the enzyme molecule. E) Allosteric regulators are often a downstream product of the pathway. C - correct answer ✔✔It is necessary to know the value of [E]t in order to determine the values of A) KM B) Vmax C) kcat D) B and C E) A, B and C B - correct answer ✔✔Prodrugs are inactive compounds that need to be cleaved in order to yield an active drug. A novel tumor therapy has recently involved the delivery of an enzyme, capable of catalyzing this cleavage reaction, to the tumor site. This is followed by administration of the prodrug, which in this instance is acting as the substrate. Suppose that there are two enzymes capable of catalyzing this reaction. Enzyme A has a KM for the prodrug of 1 µM and Enzyme B has a KM of 1 nM. Which enzyme would you use in patients? A) Enzyme A B) Enzyme B C - correct answer ✔✔Yeast glucose-6-phosphate dehydrogenase can be inhibited by a number of cellular agents whose KI values are listed below. Which is the most effective inhibitor? Which inhibitor is likely to be completely ineffective under normal cellular conditions? Inhibitor KI (M) Inorganic phosphate 1.0 x 10-1 Glucosamine-6-phosphate 7.2 x 10-4 NADPH 2.7 x 10-5 A) Most effective: inorganic phosphate; Ineffective: NADPH B) Most effective: glucosamine-6-phosphate; Ineffective: NADPH C) Most effective: NADPH; Ineffective: inorganic phosphate D) Most effective: NADPH; Ineffective: glucosamine-6-phosphate E) Most effective: glucosamine-6-phosphate; Ineffective: inorganic phosphate A - correct answer ✔✔What is the relationship between KM and [S] when an enzyme-catalyzed reaction proceeds at 90% of Vmax? A) [S] = 9 KM B) [S] = 0.9 KM C) [S] = KM D) [S] = 0.10 KM E) [S] = 10 KM A - correct answer ✔✔An insect aminopeptidase was purified and its catalytic activity was investigated using an artificial peptide substrate. The Vmax was 4.0 x 10-7 M/s and the KM was 1.4 x 10-4 M. The enzyme concentration used in the assay was 1.0 x 10-7 M. What is the catallytic efficiency of the enzyme? A) 2.8 x 104 s-1.M-1 B) 2.8 x 10-4 s-1.M-1 C) 3.5 x 10-5 s-1.M-1 D) 2.9 x 10-3 s-1.M-1 E) 3.6 x 10-3 s-1.M-1 D - correct answer ✔✔There are few examples of inhibitors that decrease Vmax but do not affect KM, these inhibitors A) affect kcat B) affect the catalytic function, but not the binding of substrate C) are called noncompetitive D) all of the above B) diffusion, secondary active transport C) facilitated transport, facilitated transport D) facilitated transport, secondary active transport E) None of the above choices are correct. D - correct answer ✔✔The drug known as Botox is a preparation of botulinum toxin. How does this account for its use by plastic surgeons to alleviate facial wrinkles? A) botulinum toxin targets SNAREs for degradation by proteolysis. B) SNAREs are necessary for transmission of signals from facial nerves to muscles via synaptic. C) SNAREs function by forming α−helical bundles to fuse synaptic vesicles with the plasma membrane D) all of the above E) none of the above B - correct answer ✔✔Which of the following is true regarding the glucose transporter? A) in addition to glucose, it will transport any other monosaccharide with six carbons B) binding of glucose causes a conformational change so that the transporter is never open on both sides of the membrane C) ATP hydrolysis prevents the transporter from working in reverse D) it is able to transport glucose into a cell against a concentration gradient E) none of the above D - correct answer ✔✔All known porins are _____ proteins composed of _____. A) monomeric; seven transmembrane α-helices B) dimeric; β-barrels C) dimeric; three transmembrane α-helices D) trimeric; β-barrels E) trimeric; four transmembrane α-helices B - correct answer ✔✔Activation of a G protein in response to hormone binding requires binding of _____ to the _____ subunit. A) GDP; β B) GTP; α C) GDP; γ D) GTP; β E) GDP; α A - correct answer ✔✔Some G protein-linked receptors are associated with a protein called RGS (regulator of G protein signaling). RGS stimulates the GTPase activity of the G protein associated with the receptor. What effect does RGS have on the signaling process? A) This will shorten the duration of signaling. B) This will lengthen the duration of signaling. C) Since the G protein has inherent GTPase activity -- this will have no effect on signaling. C - correct answer ✔✔Phorbol esters, which are compounds isolated from plants, are structurally similar to diacylglycerol. How does the addition of phorbol esters affect the signaling pathways of cells in culture? A) They would elevate the concentration of cAMP. B) They would activate protein kinase A. C) They would activate protein kinase C. D) They would activate Ras protein. E) They would stimulate lipid hormone signaling. D - correct answer ✔✔Which of the receptors below is a tyrosine kinase? A) β2-adrenergic receptor B) G protein receptor C) phospholipase C receptor D) insulin receptor D - correct answer ✔✔cAMP binds to the _____ subunits of protein kinase A allowing the tetramer to dissociate into _____. A) active subunits; an active dimer and two inactive monomers B) active subunits; two active monomers and an inactive dimer C) regulatory subunits; an active dimer and two inactive monomers D) regulatory subunits; two active monomers and an inactive dimer E) regulatory subunits; two active monomers and two inactive monomers C - correct answer ✔✔Ligand binding to a receptor tyrosine kinase causes _____ of the receptor which then _____ the next protein in the signaling pathway. A) methylation; hydrolyzes B) hydrolysis; inhibits C) phosphorylation; phosphorylates D) acylation; activates E) none of the above C - correct answer ✔✔Sarin gas [(CH3)2CHO]CH3P(O)F is a fatal nerve agent that acts as an irreversible inhibitor of the enzyme acetylcholine esterase. Acetylcholine esterase hydrolyzes acetylcholine to render it inactive in the synapse. Atropine is an antagonist to acetylcholine. Latrotoxins (black widow venom) act as agonists to acetylcholine. Which of the following physiological features would you expect to find in an individual exposed to sarin gas? Would you treat this individual with atropine or latrotoxins to reverse the symptoms? A) Increased muscle contraction; latrotoxin B) Decreased muscle contraction; latrotoxin C) Increased muscle contraction; atropine D) Decreased muscle contraction; atropine D - correct answer ✔✔Renin or chymosin is a protease similar to chymotrypsin, except that it belongs to a class of enzymes called aspartyl proteases -- in which asparatate residues are found in the active site rather than serine. Renin catalyzes the hydrolysis of a peptide bond in the protein angiotensinogen, converting it to angiotensin I, a precursor of a hormone involved in regluating blood pressure. Renin inhibitors are therefore potentially valuable in the treatment of high blood pressure. Two aspartate C) Mass spectrometry D) Edman sequencing E) Size exclusion chromatography D - correct answer ✔✔What is the conjugate base of H2PO4-? A) H2PO42- B) PO43- C) H3PO4 D) HPO42- D - correct answer ✔✔What types of bonds are present in polysaccharides? A) peptide bonds B) phosphodiester C) phosphoester D) glycosidic E) amide bonds C - correct answer ✔✔Which of the following assembles into bundles of molecules to form a thick filament? A) Collagen B) Kinesin C) Myosin D) Actin E) Tubulin D - correct answer ✔✔Which of the following does NOT exhibit quaternary structure? A) Hemoglobin B) Collagen C) Tubulin D) Myoglobin E) Keratin B - correct answer ✔✔Which technique involves the determination of protein primary structure by physically breaking a peptide into smaller fragments? A) Edman sequencing B) Mass spectroscopy C) Size exclusion chromatography D) X-ray crystallography E) SDS-PAGE electrophoresis B - correct answer ✔✔α-helix or β-sheet relates to A) primary structure B) secondary structure C) tertiary structure D) quaternary structure B - correct answer ✔✔An amino acid residue that is essential for protein structure or function could be conservatively substituted in a homologous protein. A) True B) False B - correct answer ✔✔Histones are basic proteins that bind to DNA. Which amino acids are found in abundance in histones? A) D and E B) R and K C) H and P D) W and Y E) I and L B - correct answer ✔✔Hemoglobin is a heterotetramer that has 4 identical subunits A) True B) False C - correct answer ✔✔Would the structure below be considered polar, nonpolar, or amphiphilic? (see Exam 1B #16) A) Polar B) Nonpolar C) Amphiphilic B - correct answer ✔✔The most recently added actin subunits in a microfilament contain bound ADP. A) True B) False C - correct answer ✔✔Non-polar molecules experience a small attractive force owing to A) ionic interactions B) hydrogen bonding C) London dispersion forces D) all of the above E) none of the above B - correct answer ✔✔Which of the molecules below contains an ether group? (See Exam 1B #19) A) (a) B) (b) C) (c) D) (d) E) None of the above A - correct answer ✔✔20. The higher the dielectric constant, the more __________ the compound. D) leucine E) proline C - correct answer ✔✔Given the information below, which protein will migrate to the anode at pH 5.9? *Protein pI* Myoglobin 6.8 Cytochrome c 9.3 Carbonic anhydrase 4.9 A) Myoglobin B) Cytochrome c C) Carbonic anhydrase B - correct answer ✔✔What is the pH of a 4.5 x 10^-7 M solution of [OH-]? A) 6.34 B) 7.65 C) 7.00 D) 10.25 E) 5.35 B - correct answer ✔✔Mass spectrometry is highly accurate and can therefore distinguish between the amino acids Ile and Leu. A) True B) False C - correct answer ✔✔A patient who has taken an overdose of aspirin is brought into the emergency room for treatment. She suffers from respiratory alkalosis and the pH of her blood is 7.55. What is the ratio of HCO3-/H2CO3 (pK~6.35) at normal blood pH (7.4)? A) 2.9 to 1 B) 1 to 11.2 C) 11.2 to 1 D) 1 to 2.9 E - correct answer ✔✔What is the net charge on the following peptide at pH 5? I-T-S-H-A-R-D-W-Y-R-K A) -1 B) 0 C) +1 D) +2 E) +3 A - correct answer ✔✔In carbon monoxide (CO) poisoning, CO binds to the heme of hemoglobin much more readily than oxygen. What effect will this have on the affinity of hemoglobin (Hb) for O2? Given what you know about the effect of pH on Hb, how does body pH affect Hb's affinity for CO? A) Hemoglobin will bind to less oxygen, and lower pH will decrease CO affinity. B) Hemoglobin will bind to less oxygen, and higher pH will decrease CO affinity. C) Hemoglobin will bind to more oxygen, and lower pH will decrease CO affinity. D) Hemoglobin will bind to more oxygen, and higher pH will decrease CO affinity. A - correct answer ✔✔Highly active muscle generates lactic acid by respiration so fast that the blood passing through the muscle actually experiences a drop in pH from about 7.4 to about 7.2. Under these conditions, hemoglobin releases ______ O2 than it does at pH 7.4. A) more B) less C) the same amount of E - correct answer ✔✔Which of the following amino acids is acidic? A) M B) S C) Y D) L E) D C - correct answer ✔✔Fetal hemoglobin has a higher affinity than adult hemoglobin, because A) Fetal red blood cells are more acidic than adult red blood cells. B) Fetal red blood cells are less acidic than adult red blood cells. C) The binding between BPG and hemoglobin is weaker in fetus than in adult. D) The binding between BPG and hemoglobin is stronger in fetus than in adult. E) none of the above A - correct answer ✔✔Which of the molecules below is capable of forming micelles? (See Exam 1B #37) A) (a) B) (c) C) (d) D) (e) E) Both (a) and (d) B - correct answer ✔✔Which of the following statements is (are) true? A) In any spontaneous process, the entropy of the universe decreases. B) For a spontaneous process, ΔG < 0. C) For any process to be spontaneous, ΔS of the system must be positive. D) A and C are correct. E) B and C are correct. E - correct answer ✔✔The larval form of the parasite Schistosoma mansoni infects humans by penetrating the skin. The larva secretes enzymes that catalyze the cleavage of peptide bonds between residues X and Y in the sequence -Gly-Pro-X-Y- (X and Y can be any of several amino acids). What protein is the target of these enzymes? A) keratin B) myosin C) actin E) (a) and (d) E - correct answer ✔✔Which of the following amino acids have side chains that are able to participate in forming hydrogen bonds? A) W B) I C) M D) K E) Both W and K B - correct answer ✔✔To form the coiled coil in intermediate filaments, the _________ sides of the two alpha helices come in contact with each other. A) Polar B) Nonpolar A - correct answer ✔✔At what pO2 value would myoglobin (K = 2.8 torr) be 75% saturated with O2? A) 8.4 torr B) 84 torr C) 1.2 torr D) 12 torr E) 6.2 torr B - correct answer ✔✔Which would be a more effective buffer at pH 8.0? A) 10 mM Tris (pK 8.30) B) 20 mM Tris (pK 8.30) C) They will be equally effective A - correct answer ✔✔Is the NADH molecule below being oxidized, reduced, or neither oxidized nor reduced? (See Exam 1B #51) A) Oxidized B) Reduced C) Neither C - correct answer ✔✔The oxygen-binding curves for normal hemoglobin (Hb A) and a mutant hemoglobin (Hb Great Lakes) are shown in the figure below. Which of the two hemoglobins: 1) has a higher affinity for oxygen when pO2 =20 torr; and 2) is most efficient at delivering oxygen from arterial blood (pO2 = 75 torr) to active muscle (pO2 = 20 torr)? (See Exam 1B #52) A) 1) Hb A; 2) Hb A B) 1) Hb A; 2) Hb Great Lakes C) 1) Hb Great Lakes; 2) Hb A D) 1) Hb Great Lakes; 2) Hb Great Lakes E) 1) same affinity; 2) Hb Great Lakes C - correct answer ✔✔Proinsulin is a single polypeptide, containing A, B, and C chains (structure below). Insulin is processed from proinsulin by proteases that cleave the peptide at the bonds indicated by the black arrows -- leaving only the A and B chains. An experiment was carried out in which separate samples of proinsulin and insulin were denatured or unfolded using urea and mercaptoethanol (a reducing agent). The denaturants were then removed by dialysis and the proteins allowed to renature or refold. Will renaturation produce active proteins for both samples? (See Exam 1B #53) A) Both samples will produce properly refolded and active proteins. B) Only the insulin sample will produce a properly refolded and active protein. C) Only the proinsulin sample will produce a properly refolded and active protein. D) Neither sample will produce a properly refolded and active protein. A - correct answer ✔✔Phosphofructokinase catalyzes the transfer of a phosphate group (from ATP) to fructose-6-phosphate to produce fructose-1,6-bisphosphate. The ΔH value for this reaction is -9.5 kJ/mol and the ΔG is -17.2 kJ/ mol. Based on this information, answer these questions: 1) Is the reaction exothermic or endothermic?; 2) Does entropy increase or decrease?; and 3) Which component makes a greater contribution to the free energy value -- the ΔH or ΔS value? A) 1) exothermic; 2) entropy increases; 3) ΔH makes a greater contribution to the value of ΔG B) 1) exothermic; 2) entropy decreases; 3) ΔH makes a greater contribution to the value of ΔG C) 1) endothermic; 2) entropy increases; 3) ΔS makes a greater contribution to the value of ΔG D) 1) exothermic; 2) entropy increases; 3) ΔS makes a greater contribution to the value of ΔG E) 1) endothermic; 2) entropy increases; 3) ΔH makes a greater contribution to the value of ΔG B - correct answer ✔✔How many mL of a 2.0-M solution of boric acid (pK 9.24) must be added to 600 mL of a solution of 10 mM sodium borate in order for the pH to be 9.45? A) 3.7 mL B) 1.9 mL C) 4.9 mL D) 19.0 mL E) 2.4 mL D - correct answer ✔✔Calculate the pH of a 1-L solution to which has been added 6.0 mL of 1.5 M acetic acid and 5.0 mL of 0.4 M sodium acetate (pK 4.76). A) 5.41 B) 3.27 C) 4.76 D) 4.11 B - correct answer ✔✔Biochemists sometimes link a recombinant protein to a protein known as green fluorescent protein (GFP). The fluorophore in GFP (below) is a derivative of 3 amino acids that undergo cyclization of the polypeptide followed by an oxidation. Identify: (a) the 3 amino acids; (b) the bond that results from cyclization; and (3) the bond the results from oxidation. (See Exam 1B #57) A) (i) S-Y-A; (ii) bond c; (iii) bond a B) (i) S-Y-G; (ii) bond a; (iii) bond b C) (i) S-Y-G; (ii) bond a; (iii) bond c D) (i) S-Y-A; (ii) bond a; (iii) bond b E) (i) T-Y-A; (ii) bond c; (iii) bond a A) Increases it B) Decreases it C) No effect A - correct answer ✔✔Which of the following has amino acid side chains that can ALL act as either an acid or a base catalyst? A) Lys, Cys, Asp B) Asp, Gly, His C) Tyr, Glu, Gly D) Phe, Ser, His E) Glu, Gln, Tyr D - correct answer ✔✔Which of the following curves shows the appropriate relationship between [E] and time? (See Exam 2C #11) A) (a) B) (b) C) (c) D) (d) E) (e) B - correct answer ✔✔In which type of reversible inhibition does the inhibitor have no impact on substrate binding? A) competitive B) noncompetitive C) uncompetitive D) mixed A - correct answer ✔✔The ability of receptors to adapt to long-term stimulation by responding to changes in stimulation is called A) desensitization B) cross-talk C) signal transduction D) dual-specificity E) auto-inhibition D - correct answer ✔✔Which of the following is not a serine protease? A) Chymotrypsin B) Trypsin C) Elastase D) Collagenase B - correct answer ✔✔Mutant Ras proteins have been found to be associated with various types of cancer (uncontrolled cell growth). What is the likely effect of the mutation on Ras function? A) Ras GTPase activity is elevated. B) Ras is unable to hydrolyze GTP. C) Ras is unable to bind either GDP or GTP. B - correct answer ✔✔Which of the following statements about the mechanism of the Na+/K+ ATPase is correct? A) In the Na+/K+ ATPase reaction cycle, Na+ is pumped into the cell when the protein is dephosphorylated. B) In the Na+/K+ ATPase reaction cycle, Na+ is pumped out of the cell when the protein is phosphorylated. C) In the Na+/K+ ATPase reaction cycle, Na+ is pumped into the cell when the protein is phosphorylated. D) In the Na+/K+ ATPase reaction cycle, Na+ is pumped out of the cell when the protein is dephosphorylated. B - correct answer ✔✔What factor(s) are important in the high selectivity of the K+ channel? A) The pore is lined with negatively-charged carboxyl groups to coordinate the positive ion. B) A network of Tyr residues ensures that smaller ions like Na+ will be excluded. C) A loop connecting two of the helices constricts the pore to make it specific for K+. D) Coordinated H2O molecules restrict the size of the cation that can be transported. E) A and B are both factors. D - correct answer ✔✔Which of the following is not an example of a passive-mediated transporter? A) aquaporin B) ion channels C) glucose transporter, GLUT1 D) Na+/K+ transporter E) none of the above A - correct answer ✔✔Which of the following statements regarding catalytic efficiency is TRUE? A) It reflects both substrate binding and catalytic events. B) The quantitative measure is KM/kcat. C) It is the apparent first order rate constant for ES formation. D) It increases with KM. E) It decreases with kcat. C - correct answer ✔✔What is the kcat for a reaction in which Vmax is 0.4 mmoles/min and the reaction mixture contains 5 × 10-6micromoles of enzyme? A) 2 x 10-14 min-1 B) 2 x 10-11 min-1 C) 8 x 107 min-1 D) 4 x 108 min-1 E) 8 x 109 min-1 B - correct answer ✔✔Which of the following would be likely to form a bilayer in a solution containing only the lipid indicated? C - correct answer ✔✔In the catalytic mechanism of chymotrypsin, what is represented by the two hills in the reaction coordinate? A) His 57 acting as a base catalyst twice in the mechanism B) Water entering the active site C) The tetrahedral intermediates, where oxygen acts as a nucleophile attacking the carbonyl carbon D) His 57 acting as an acid catalyst, donates a proton to the nitrogen of the scissile peptide bond E) The departure of the C-terminal portion of the cleaved peptide B - correct answer ✔✔When a nerve cell is stimulated, the membrane potential increases from -70 mV to +50 mV. Calculate the ratio of [Na+]in/[Na+]out in the depolarized nerve cell at a body temperature of 37oC. A) 7.3 B) 6.5 C) 2.36 D) 0.42 B - correct answer ✔✔The GTPase activity of the alpha subunit of the G-protein is similar to the activity of which class of enzymes? A) lyases B) hydrolases C) oxidoreductases D) transferases E) ligases E - correct answer ✔✔Desensitization of a G protein-coupled receptor is caused by phosphorylation of the receptor by a specific kinase. What protein recognizes the phosphorylated receptor? A) phospholipase C B) the G protein γ subunit C) cAMP phosphodiesterase D) adenosine receptor E) arrestin B - correct answer ✔✔Given the plot below, estimate the value of KM for Enzyme B. (See Exam 2C #33) A) 7 µM B) 5 µM C) 2 µM D) 3.5 µM B - correct answer ✔✔Which of the structures below would represent a glycerophospholipid? (See Exam 2C #34) A) A B) B C) C C or D - correct answer ✔✔A culture of bacteria growing at 37oC was shifted to 25oC. How would you expect this shift to alter the fatty acid composition of the membrane phospholipids? A) New phospholipids having longer chains and a higher degree of saturation would be synthesized. B) New phospholipids having longer chains and a higher degree of unsaturation would be synthesized. C) New phospholipids having shorter chains and a higher degree of unsaturation would be synthesized. D) New phospholipids having shorter chains and a higher degree of unsaturation would be synthesized. E - correct answer ✔✔The enzyme that catalyzes the reaction below would be classified as a(n): (See Exam 2C #36) A) Oxidoreductase B) Lyase C) Ligase D) Hydrolase E) Isomerase D - correct answer ✔✔The enzyme phenylalanine hydroxylase (PAH) catalyzes the hydroxlyation of phenylalanine to form tyrosine and is deficient in patients with the disease phenylketonuria (PKU). The KM of PAH for Phe is 500 µM and the Vmax is 7.5 µmol/min/mg. What is the velocity of the reaction when the concentration of Phe is 0.15 mM? A) 5.8 µmol/min/mg B) 102 µmol/min/mg C) 0.010 µmol/min/mg D) 1.7 µmol/min/mg E) 1.7 µM E - correct answer ✔✔Integral membrane proteins that act to fuse and link membranes are called: A) myelin sheaths B) porins C) sphingolipids D) all of the above E) none of the above A - correct answer ✔✔Under certain conditions, peptide bond formation is more thermodynamically favorable than peptide bond hydrolysis. Would you expect chymotrypsin to catalyze peptide bond formation? A) Yes B) No C) Cannot be determined D - correct answer ✔✔Signal transduction can be mediated by two different types of receptors that use different pathways of activation. What do they share in common? A) They are both transmembrane proteins. B) The process begins with a conformational change induced by ligand binding. C) Cl- ions will flow into the cell and contribute to excitability. D) Cl- ions will flow into the cell and diminish excitability. C - correct answer ✔✔The kinetics of an enzyme is measured as a function of substrate concentration in the presence and absence of 100 µM inhibitor and the data plotted as in the graphs below (µmol/min-1 vs. µM-1). Based on these data, answer the following questions: 1) what type of inhibition is indicated; and 2) what is the true value of Vmax? (See Exam 2C #47) A) Competitive inhibitor; Vmax = 4.5 µmol/min B) Uncompetitive inhibitor; Vmax = 8.9 µmol/min C) Noncompetitive inhibitor; Vmax = 45 µmol/min D) Mixed inhibitor; Vmax = 8.9 µmol/min E) Competitive inhibitor; Vmax = 45 µmol/min E - correct answer ✔✔Which of the following terms indicates that the citric acid cycle is both catabolic and anabolic in nature? A) cataplerotic B) amphipathic C) anaplerotic D) diabolic E) amphibolic A - correct answer ✔✔Which of the choices below would be an accurate classification of the structure below? (See Exam 3B #2) A) aldohexose B) ketohexose C) aldopentose D) ketopentose B - correct answer ✔✔The reaction that converts glyceraldehyde-3-phosphate to 1,3- bisphosphoglycerate consumes 1 molecule of ATP. A) True B) False B - correct answer ✔✔Where is succinate dehydrogenase located? A) mitochondrial matrix B) mitochondrial inner membrane C) mitochondrial inter-membrane space D) mitochondrial outer membrane E) none of the above D - correct answer ✔✔Gluconeogenesis is most active in the _____. A) muscles B) brain C) heart D) liver E) kidneys A - correct answer ✔✔Which of the following metabolic conversions is considered to be the major control point of glycolysis? A) Fructose-6-phosphate → fructose-1,6-bisphosphate B) pyruvate → lactate C) 2-phosphoglyerate → phosphoenolpyruvate D) Fructose-1,6-bisphosphate → dihydroxyacetone phosphate + glyceraldehyde-3-phosphate E) Glucose → glucose-6-phosphate A - correct answer ✔✔ATP contains one ________ bond and two ______ bonds. A) phosphoester; phosphoanhydride B) phosphoanhydride; phosphoester C) amide; phosphoanhydride D) phosphoester; glycosidic E) glycosidic; amide B - correct answer ✔✔When a reaction is at equilibrium, the ΔG is equal to _____. A) 1 B) 0 C) -1 D) ΔG°' E) none of the above B - correct answer ✔✔Electrons that enter at Complex II of the electron transport chain generate enough protons to make ~3 ATP. A) True B) False B - correct answer ✔✔Which mechanism for degrading cellular proteins involves the use of an organelle containing hydrolytic enzymes? A) proteasome B) lysosome C) GroEL/ES D) hydrolosome E) none of the above A - correct answer ✔✔Any sugar that has a free aldehyde group is called a(n) _____. A) reducing sugar B) non-reducing sugar C) ketose D) aldohexose E) 8 A - correct answer ✔✔What cofactor would be needed to carry out the following reaction, which is part of the catabolism of even-chain fatty acids? (See Exam 3B #20) A) NAD+ B) NADP+ C) NADH D) NADPH E) FAD D - correct answer ✔✔The Keq is 0.503 at 25°C for the following reaction. What is the ΔG°' for this reaction? D-Glucose-6- phosphate → D-Fructose-6-phosphate A) -1,700 J/mol B) -2,870 J/mol C) +143 J/mol D) +1700 J/mol E) none of the above A - correct answer ✔✔Which of the following is correct concerning the metabolic reaction shown below? Pyruvate + NAD+ + CoA-SH → Acetyl-CoA + NADH + H+ + CO2 A) This reaction is an oxidative decarboxylation. B) The enzyme that catalyzes this metabolic conversion is activated by high concentrations of ATP. C) This reaction is catalyzed by an enzyme in the cytosol of the cell. D) The enzyme that catalyzes this reaction contains a pyridoxal phosphate prosthetic group. E) This reaction is sometimes referred to as an anaplerotic reaction in that it "refills" the citric acid cycle when intermediates have been removed for biosynthesis. A - correct answer ✔✔Would phosphoenolpyruvate (PEP) stabilize the T form, the R form, or neither form of PFK-1 in bacteria? A) T form B) R form C) Neither form A - correct answer ✔✔NADPH used in lipid biosynthesis is produced in _____. A) the pentose phosphate pathway B) the citric acid cycle C) glycolysis D) gluconeogenesis E) none of the above A - correct answer ✔✔Which of the following functon solely as structural molecules? A) chitin B) cellulose C) amylose D) B and C E) A, B and C C - correct answer ✔✔A major allosteric regulator of both glycolysis and gluconeogenesis is: A) 2,3 bisphosphoglycerate B) 1,3 bisphosphoglycerate C) fructose 2,6 bisphosphate D) fructose 1,6 bisphosphate E) none of the above E - correct answer ✔✔Which of the following coenzymes is directly responsible for the oxidation of the hydroxyethyl group to the acetyl group? A) coenzyme A B) thiamine pyrophosphate C) FAD D) NAD+ E) lipoamide A - correct answer ✔✔The reduction potentials of all prosthetic groups of Complex I have reduction potentials between _____ and _____. A) NAD+; ubiquinone B) NADH; ubiquinol C) FAD; ubiquinone D) ubiquinone; oxygen E) ubiquinone; cytochrome c C - correct answer ✔✔Hexokinase is an example of a(n) _____ enzyme A) ligase B) hydrolase C) transferase D) isomerase B or D - correct answer ✔✔How many electrons are transferred from one acetyl group when it is converted to two carbon dioxide molecules in the citric acid cycle? A) 2 B) 4 C) 6 D) 8 E) 10 B - correct answer ✔✔What are the substrates for reaction 1 of the TCA cycle? A) pyruvate and lactate B) acetyl CoA and oxaloacetate D - correct answer ✔✔Which of the following best describes the function of cytochrome c oxidase? A) Cytochrome c oxidase oxidizes two consecutive cytochrome c molecules, via two-electron transfers, while simultaneously reducing one O2 to two H2O. B) Cytochrome c oxidase oxidizes two consecutive cytochrome c molecules, via two-electron transfers, while simultaneously reducing two O2 to two H2O. C) Cytochrome c oxidase oxidizes four consecutive cytochrome c molecules, via one-electron transfers, while simultaneously reducing two O2 to two H2O. D) Cytochrome c oxidase oxidizes four consecutive cytochrome c molecules, via one-electron transfers, while simultaneously reducing one O2 to two H2O. B - correct answer ✔✔How is the activity of the pyruvate dehydrogenase complex affected by a high [acetyl-CoA]/[CoA] ratio? A) Activity increases B) Activity decreases C) Activity is unaffected B - correct answer ✔✔What is the ΔG°' for the reduction of pyruvate to lactate by NADH given the following half reactions? pyruvate- + 2H+ + 2e- → lactate- ε°' = (-) 0.185 NAD+ + H+ + 2e- → NADH ε°- = (-) 0.315 A) -96.5 kJ/mol B) -25.1 kJ/mol C) -12.5 kJ/mol D) 25.1 kJ/mol E) 96.5 kJ/mol C - correct answer ✔✔Which of the following are fuel-storage molecules that humans can utilize? A) chitin B) cellulose C) amylose D) B and C E) A, B and C C - correct answer ✔✔Which enzyme of the pyruvate dehydrogenase complex is responsible for regenerating an oxidized lipoamide cofactor? A) E1 B) E2 C) E3 B - correct answer ✔✔In bacterial cells, _____ is an activator of phosphofructokinase while _____ is an inhibitor. A) glucose-6-phosphate; ATP B) ADP; phosphoenolpyruvate C) fructose-2,6-bisphosphate; fructose-6-phosphate D) AMP; glyceraldehyde-3-phosphate E) citrate; ADP B - correct answer ✔✔Complex III accepts electrons from _____ and transfers them to _____. A) cytochrome c; cytochrome a B) ubiquinol; cytochrome c C) ubiquinone; cytochrome c D) ubiquinol; cytochrome b E) ubiquinone; cytochrome a C - correct answer ✔✔The glycolytic pathway in the thermophilic bacterium Thermoproteus tenax differs from the pathway that we have studied in this course. The phosphofructokinase reaction in T. tenax is reversible and uses a phosphoryl group from pyrophosphate rather than ATP. In addition, T. tenax has a nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPDH) that catalyzes the reaction shown below. The remainder of the pathway is idential to the one we studied. T. tenax relies exclusively on glycogen stores as a source of energy. Based on this information, determine the ATP yield for one molecule of glucose oxidized by this bacterium. (See Exam 3B #46) A) 0 B) 1 C) 2 D) 3 E) 4 C - correct answer ✔✔In a muscle cell at 37°C, if the concentrations of pyruvate and lactate are 100 µM and 50 µM respectively, what is the actual reduction potential if ε°' for pyruvate reduction is -0.185 V? A) -0.194 V B) -0.186 V C) -0.176 V D) 0.176 V E) 0.194 V B - correct answer ✔✔Trypanosomes (intracellular parasite that causes malaria) while in the blood stream of human hosts obtain all their energy from glycolysis of glucose (obtained from the host) and excrete the pyruvate into the host's blood stream. The trypanosomes do not carry out oxidative phosphorylation. What type of metabolic reaction must trypanosomes have? A) A method for generation of NADH B) A method for generation of NAD+ C) A method for generation of FADH2 D) A method for generation of FAD E) none of the above are correct C - correct answer ✔✔The carbon fixing reactions occur in the _____ . A) thylakoid lumen B) thylakoid membrane C) stroma D) space between inner and outer chloroplast membrane E) cytosol D - correct answer ✔✔The nonessential amino acids _____ and _____ are synthesized from essential amino acids. A) cysteine B) tyrosine C) methionine D) A and B E) B and C D - correct answer ✔✔What molecule is able to move across the mitochondrial membrane and is thus used to "transfer" acetyl-CoA from the mitochondria to the cytosol? A) acetate B) oxaloacetate C) α-ketoglutarate D) citrate E) succinate B - correct answer ✔✔The active group of photosystem I is known as _____. A) P800 B) P700 C) P660 D) P650 E) P450 D - correct answer ✔✔Which of the lipoproteins is responsible for removing cholesterol from cells? A) chylomicron B) VLDL C) LDL D) HDL E) VHDL E - correct answer ✔✔Which of the following is NOT a possible fate of cholesterol? A) Incorporation into a cell membrane D) Precursor of bile acids C) Precursor of testosterone and estrogen B) Acylation for storage E) Catabolism to ketone bodies D - correct answer ✔✔Researchers have identified several metabolites whose concentrations in urine may be elevated in prostate cancer. One of these metabolites is sarcosine (N-methylgycine), which can be converted to glycine by demethylation (below). Elevation of sarcosine in the blood can also occur due to nutritional deficiency. What cofactor is missing in these cases? (See Exam 4B #15) A) pyridoxyl-5'-phosphate B) biotin C) lipoamide D) tetrahydrofolate E) thiamine pyrophosphate C - correct answer ✔✔During fatty acid oxidation methylene groups are oxidized and carbonyl groups are generated, yet no O2 is consumed. How is this possible? A) The oxygen is derived from a hydroxyl group on the cofactor. B) The oxygen is derived from a hydroxyl group of glucose. C) The oxygen is derived from water. D) The oxygen is derived from a pentose phosphate pathway intermediate. E) None of the above E - correct answer ✔✔Which of the following citric acid cycle intermediates can be converted to aspartate via transamination? A) succinate B) fumarate C) α-ketoglutarate D) citrate E) oxaloacetate B - correct answer ✔✔Under conditions of very high light intensity, excess absorbed solar energy is dissipated by the action of "photoprotective" proteins in the thylakoid membrane. How would the proton gradient across the membrane influence these proteins? A) High pH in the lumen would activate these proteins B) Low pH in the lumen would activate these proteins C) Low pH in the stroma would activate these proteins B - correct answer ✔✔The expression of phosphoglycerate dehydrogenase, which catalyzes the first step of serine biosynthesis (below), is dramatically elevated in some cancers, which are highly metabolically active. Given this information, what metabolic pathway would be the primary means of meeting the cancer cell's energy needs? (See Exam 4B #19) A) Glycolysis B) TCA cycle C) Fatty acid oxidation D) Catabolism of ketone bodies E) Nucleotide catabolism B - correct answer ✔✔When glucose is unavailable, the liver begins to break down fatty acids to supply the rest of the body with metabolic fuel. Why is the acetyl-CoA generated by fatty acid oxidation, diverted to ketogenesis rather than being catabolized by the TCA cycle? A) Excess acetyl-CoA binds to and inhibits the citrate transporter used in the TCA cycle. B) The oxaloacetate needed in the first reaction of the TCA cycle is being diverted to gluconeogenesis. C) Acetyl-CoA is a feedback inhibitor of the succinyl dehydrogenase enzyme that functions in the TCA cycle. D) A and B are true. E) A and C are true. C - correct answer ✔✔What is the product of the following transaminase reaction: serine + α- ketoglutarate --> glutamate + _______ (See Exam 4B #29) A) A B) B C) C D) D B - correct answer ✔✔A deficiency of carnitine results in muscle cramps, which are exacerbated by fasting or exercise. What is the biochemical explanation for this muscle cramping? A) Carnitine is used to directly contribute acetyl-CoA to the TCA cycle, to thereby generate energy. B) Carnitine is the acyl carrier that allows β-oxidation of fatty acids to occur in the mitochondrial matrix, to thereby generate energy. C) Carnitine is the cofactor used by acyl-CoA dehydrogenase in the first step of β-oxidation. D) Carnitine directly donates electrons to the electron transport chain, which generates the proton gradient utilized in ATP synthesis. B - correct answer ✔✔In plants and cyanobacteria, Photosystem II ______, and Photosystem I ______. A) oxidizes H2O, reduces NAD+ B) oxidizes H2O, reduces NADP+ C) oxidizes O2, reduces FAD D) oxidizes H2O, reduces FAD E) none of the above are true D - correct answer ✔✔Which of the following correctly describes the general synthesis of purine nucleotides? A) The basic ring structure, orotate, is synthesized and then linked to PRPP B) The basic ring structure, orotate, is synthesized stepwise on PRPP C) The basic ring structure, inosine, is synthesized and then linked to PRPP D) The basic ring structure, inosine, is synthesized stepwise on PRPP E) none of the above A - correct answer ✔✔Phosphatidylcholine synthesis begins with activation of choline followed by addition of _________. A) diacylglycerol B) phosphatidate C) glycerol-3-phosphate D) dihydroxyacetone phosphate E) glycerol D - correct answer ✔✔Which of the following amino acids is a source of both carbon and nitrogen for UMP? A) Glu B) Gln C) Gly D) Asp E) Asn B - correct answer ✔✔The Eo' of the half reaction: N2 + 6 H+ + 6 e- <----> 2 NH3 is -0.34 V. The reduction potential of the nitrogenase component that donates electrons for nitrogen reduction is about -0.29V. ATP hydrolysis apparently induces a conformational change in the protein that alters its reduction potential . Does this change increase or decrease the Eo' of the electron donor? A) Increase B) Decrease A - correct answer ✔✔Complete this reaction: Acetyl-CoA + 7 malonyl-CoA + 14 NADPH + 7 H+ → A) palmitate (16:0) + 7 CO2 + 14 NADP+ + 8 CoA + 6 H2O B) stearate (18:0) + 7 CO2 + 14 NADP+ + 8 CoA + 6 H2O C) palmitate (16:0) + 7 CO2 + 14 NADP+ + 7 CoA + 6 H2 D) stearate (18:0) + 14 NADP+ + 8 CoA + 6 H2O D - correct answer ✔✔When the antifungal agent myxothiazol is added to a suspension of chloroplasts, the PQH2/PQ ratio increases. Where does myxothiazol inhibit electron transfer? A) Complex I B) Photosystem I C) Photosystem II D) cytochrome b6f E) plastocyanin A - correct answer ✔✔The breakdown product of leucine is acetyl-CoA and acetoacetate. This amino acid would be classified as A) ketogenic C) Both glucogenic and ketogenic B) glucogenic A - correct answer ✔✔How many plastoquinone molecules will be involved in the transfer of 4 electrons from PSII to cytochrome b6f complex? A) 4 B) 2 C) 6 D) 8 E) 1 C - correct answer ✔✔The final carrier of electrons from PSI is ____, which can then dispose of electrons to produce either ATP or NADPH. A) plastocyanin B - correct answer ✔✔What is the total energy cost (in ATP-equivalents) of the Urea cycle? How many ATP molecules are actually involved in these steps? A) 3 ATP-equivalents cost; 3 ATP molecules involved B) 4 ATP-equivalents cost; 3 ATP molecules involved C) 4 ATP-equivalents cost; 4 ATP molecules involved D) 8 ATP-equivalents cost; 4 ATP molecules involved E) 6 ATP-equivalents cost; 4 ATP molecules involved A - correct answer ✔✔Which of the proteins below has a long neck region? A) Myosin B) Kinesin C) Actin D) Tubulin E) Collagen B - correct answer ✔✔Which of the following are typical hydrogen bond interactions? A) N-H, H-H, S-H, H-C B) N-H, O-H, S-H C) O-H, S-H, C-O D) N-H, S-H, H-Si E) none of the above E - correct answer ✔✔Which of the chemical bonds listed below is NOT generally found in biological polymers? A) glycosidic bond B) amide bond C) phosphodiester bond D) None of the above are found in biological polymers. E) All of the above are found in biological polymers. A - correct answer ✔✔Which of the following proteins would elute first in size exclusion chromatography? (Note: kDa = kiloDalton; 1 Da = 1 g/mol) A) Hemoglobin (64.5 kDa) B) Myoglobin (16.7 kDa) C) Actin (42.0 kDa) C - correct answer ✔✔Which of the molecules below contains an ester group? (See Conflict Exam 1A #5) A) (a) B) (b) C) (c) D) (d) E) None of the above A - correct answer ✔✔Collagen is a homotrimer that has 3 identical subunits A) True B) False A - correct answer ✔✔The most stable type of β-pleated sheet is in a(n) __________ conformation. A) antiparallel B) parallel C) antiparallel or parallel B - correct answer ✔✔What is the sign of the entropy change when water freezes? A) Positive B) Negative C) No change A - correct answer ✔✔What polymeric molecule forms a more regular structure, DNA or protein? A) DNA B) protein A - correct answer ✔✔Which technique involves the determination of protein primary structure by a chemical method? A) Edman sequencing B) Mass spectroscopy C) Size exclusion chromatography D) X-ray crystallography E) SDS-PAGE electrophoresis B - correct answer ✔✔In a muscle cell, the arrangement in which hundreds of myosin tails associate together, with the head domains sticking out is referred to as A) thin filament B) thick filament C) none of the above E - correct answer ✔✔What is the pH of a 4.5 x 10-7 M solution of [OH-]? A) 6.35 B) -6.35 C) -7.65 D) 7.00 E) 7.65 B - correct answer ✔✔Since the peptide bond has partial double bond character, the atoms involved in the peptide bond are nonpolar A) True B) False C) The change in tertiary conformation results in a change in quaternary structure. D) The His F8 residue moves between two Thr residues when O2 binds. B - correct answer ✔✔Several common amino acids are modified to produce biologically important amines. Serotonin is a neurotransmitter synthesized in the brain that has been linked to depression, aggression, and hyperactivity when present at levels lower than normal. Given the structure below, from what amino acid is serotonin derived? (See Conflict Exam 1A #24) A) Y B) W C) T D) F E) P C - correct answer ✔✔If you altered the structure of a biological molecule that had a pI of 9, so that it gained one new carboxyl group, what would be the effect on its pI? A) pI > 9 B) pI = 9 C) pI < 9 D - correct answer ✔✔Phosphorylation of a hydroxyl group is a common covalent modification present in proteins. Which of the 20 common amino acids was phosphorylated to yield the structure below? (See Conflict Exam 1A #26) A) Ser B) Tyr C) Leu D) Thr E) Val D - correct answer ✔✔What is the concentration of a lactic acid buffer (pK 3.9) that contains 0.25 M CH3CH(OH)COOH and 0.15 M CH3CH(OH)COO-? What is the pH of the buffer? A) 0.25 M; pH 0.60 B) 0.25 M; pH 4.00 C) 0.40 M; pH 8.23 D) 0.40 M; pH 3.68 E) 0.15 M; pH 6.23 A - correct answer ✔✔Highly active muscle generates lactic acid by respiration so fast that the blood passing through the muscle actually experiences a drop in pH from about 7.4 to about 7.2. Under these conditions, hemoglobin releases ______ O2 than it does at pH 7.4. A) more B) less C) the same amount of A - correct answer ✔✔In the developing fetus, fetal hemoglobin (Hb F) is synthesized beginning at the third month of gestation and continuing until birth. After the baby is born, the concentration of Hb F declines and is replaced with adult hemoglobin (Hb A), as synthesis of the γ chain declines and synthesis of the β chain increases. By the time the baby is six months old, 98% of its hemoglobin is Hb A. In the graph below, which curve represents fetal hemoglobin? (See Conflict Exam 1A #29) A) A B) B A - correct answer ✔✔A patient who has taken an overdose of aspirin is brought into the emergency room for treatment. She suffers from respiratory alkalosis and the pH of her blood is 7.55. What is the ratio of HCO3-/H2CO3 (pK ~6.35) in the patient's blood? A) 15.8 to 1 B) 1 to 15.8 C) 3.32 to 1 D) 1 to 3.32 B - correct answer ✔✔Formation of hydrogen bonds is fundamental to the assembly of the DNA double helix. How many potential H-bond donor groups are present in the nitrogenous base of TTP below? (See Conflict Exam 1A #31) A) 0 B) 1 C) 2 D) 3 E) 4 E - correct answer ✔✔The larval form of the parasite Schistosoma mansoni infects humans by penetrating the skin. The larva secretes enzymes that catalyze the cleavage of peptide bonds between residues X and Y in the sequence -Gly-Pro-X-Y- (X and Y can be any of several amino acids). What protein is the target of these enzymes? A) keratin B) myosin C) actin D) tubulin E) collagen C - correct answer ✔✔Formation of the double helix of DNA results in a change in free energy (ΔG) of - 54 kJ/mol at pH 7.0 in 1 M NaCl at 25oC. The heat released represents a change of -251 kJ/mol. For this process, calculate the entropy change for double helix formation. A) +661 J/mol B) 0.66 J/mol C) -661 J/mol D) -635 J/mol E) -7880 J/mol B - correct answer ✔✔Is the pyruvate molecule below being oxidized, reduced, or neither oxidized nor reduced? (See Conflict Exam 1A #34) A) Oxidized B) Reduced B) Polar; does not readily dissolve C) Nonpolar; does not readily dissolve D) Nonpolar; readily dissolves E) Amphipathic; does not readily dissolve C - correct answer ✔✔Of the six proteins, actin, myosin, tubulin, kinesin, keratin, and collagen, which are not motor proteins but can undergo structural changes? A) keratin and collagen B) myosin and kinesin C) actin and tubulin D) actin, myosin, tubulin, and kinesin E) none of the above are correct C - correct answer ✔✔If a reaction has a ΔG of -400 kJ/mol what can you infer about this reaction? A) The reaction is exothermic. B) The reaction is endothermic. C) The reaction is spontaneous. D) The reaction is non-spontaneous. C - correct answer ✔✔Which would be a more effective buffer at pH 8.0? A) 10 mM boric acid (pK 9.24) B) 10 mM borate (pK 9.24) C) They will be equally effective C - correct answer ✔✔A coupled reaction always involves A) oxidation and reduction. B) esterification. C) reactions that produce energy and reactions that consume energy. D) ATP as a reactant. E) Both B and D must be true. C - correct answer ✔✔The motor activity of kinesin requires the free energy of hydrolysis of A) GTP B) CTP C) ATP D) UTP E) none of the above C - correct answer ✔✔Which of the molecules below is capable of forming bilayers? (See Conflict Exam 1A #48) A) (a) B) (c) C) (d) D) (e) E) Both (a) and (d) E - correct answer ✔✔Which of the following proteins contain polypeptide chains that associate in a coiled-coil interaction? A) Actin B) Keratin C) Myosin D) Aand B E) B and C D - correct answer ✔✔At what pO2 value would myoglobin (K = 2.8 torr) be 85% saturated with O2? A) 1.6 torr B) 159 torr C) 2.3 torr D) 15.9 torr E) 6.2 torr C - correct answer ✔✔Identify the amino acid below and classify it by polarity. (See Conflict Exam 1A #51) A) D, polar B) D, nonpolar C) E, polar D) M, nonpolar E) Q, polar A - correct answer ✔✔How many mL of a 5.0-M solution of sodium borate must be added to 200 mL of a solution of 50 mM boric acid (pK 9.24) in order for the pH to be 9.6? A) 4.6 mL B) 46.0 mL C) 22.9 mL D) 2.29 mL E) 6.2 mL C - correct answer ✔✔A fusion protein can be synthesized in which the protein carries a specific amino acid sequence or tag. These tags are useful in identifying the proteins in various types of experiments. Fusion proteins with the FLAG epitope carry the sequence illustrated below. What is this sequence? Will the FLAG sequence be displayed on the surface of the protein? Why? (See Conflict Exam 1A #53) A) A-F-R-D-D-D-D-R; Yes, it will be on the surface becaue it is very hydrophilic. B) A-Y-K-E-E-E-E-K; Yes, it will be on the surface becaue it is very hydrophilic. C) D-Y-K-D-D-D-D-K; Yes, it will be on the surface becaue it is very hydrophilic. D) D-Y-K-D-D-D-D-K; Yes, it will be on the surface becaue it is very hydrophobic. E) A-Y-R-D-D-D-D-R; No, it will not be on the surface becaue it is very hydrophobic. D) Epimers E) Both B and D A - correct answer ✔✔Which of the ten reactions of glycolysis are oxidation-reductions? A) Reaction 6 B) Reaction 3 C) Reactions 7 and 10 D) Reactions 1 and 3 E) Reaction 2 D - correct answer ✔✔For eukaryotes, where are the Complexes of electron transport located? A) cytosol B) outer mitochondrial membrane C) mitochondrial intermembrane space D) inner mitochondrial membrane E) mitochondrial matrix C - correct answer ✔✔Which of the following does NOT represent the biochemical standard state? A) 1 M substrate concentrations B) 1 atm pressure C) 37oC temperature D) pH 7.0 E) 55.5 M water concentration C - correct answer ✔✔How many NADH are produced when one acetyl group is oxidized in the citric acid cycle? A) 1 B) 2 C) 3 D) 4 E) more than 4 B - correct answer ✔✔The oxidative reactions of the pentose phosphate pathway produce A) NADH B) NADPH C) FADH2 D) QH2 E) FMN D - correct answer ✔✔Which of the following enzymes catalyzes the transfer of a phosphoryl group from ATP to glucose? A) aldolase B) phosphoglucose isomerase C) glucose-6-phosphatase D) hexokinase E) phosphoglucose mutase E - correct answer ✔✔Amino acids can be converted to _____. A) carbohydrates B) fatty acids C) nucleotides D) peptides E) all of the above A - correct answer ✔✔Which of the five steps of the pyruvate dehydrogenase complex reaction is metabolically irreversible? A) Step 1 (decarboxylation) B) Step 2 (oxidation of hydroxyethyl) C) Step 3 (transfer of acetyl group to CoA) D) Step 4 (oxidation of lipoamide group) E) Step 5 (electron transfer to NAD+) A - correct answer ✔✔How many protons are transported from the matrix to the intermembrane space by Complex II? A) 0 B) 2 C) 4 D) 6 E) 8 D - correct answer ✔✔The molecules α-D-glucose and β-D-glucose are examples of A) anomers B) epimers C) enantiomers D) Both A and B D - correct answer ✔✔For every two electrons transferred from NADH to oxygen, _____ protons are pumped from the matrix to the intermembrane space. A) 4 B) 6 C) 8 D) 10 E) 12 B - correct answer ✔✔Which of the choices that follow would be an accurate classification of the carbohydrate structure below? (see picture on #14) A) aldopentose C - correct answer ✔✔Consider the reaction C <−−> D, which has Keq = 0.1. Calculate the ΔG value for the reaction at 37oC when the concentrations of C and D are 0.9 mM and 0.1 mM, respectively. A) +0.23 kJ/mol B) -0.042 kJ/mol C) +0.042 kJ/mol D) -7.9 kJ/mol E) -0.23 kJ/mol C - correct answer ✔✔Which of the following would require a shuttle system in order to pass electrons to the electron transport chain? A) NADH produced in the Kreb's cycle B) QH2 produced in the Kreb's cycle C) NADH produced during glycolysis D) NADPH produced during glycolysis E) QH2 produced during fatty acid oxidation A - correct answer ✔✔How would the enzymes hexokinase and phosphofructokinase be affected by anaerobic conditions? A) Activity of both would increase. B) Activity of both would decrease. C) Activity of hexokinase would increase and activity of phosphofructokinase would be the same. D) Activity of hexokinase would the same but activity of phosphofructokinase would increase. E) There would be no change in the activity of either enyzme. E - correct answer ✔✔The ΔGo' value for the hexokinase reaction is -16.7 kJ/mol, while the ΔG value under cellular conditions is similar. What is the ratio of glucose-6-phosphate to glucose under standard conditions if the ratio of [ATP] to [ADP] is 10:1? A) 8.5 x 10-3 B) 1.2 x 10-4 C) 5.5 x 107 D) 85 E) 8.5 x 103 D - correct answer ✔✔Shown below is the Fischer projection of D-ribulose. Which of the choices below would be a proper representation of the Haworth projection of α-D-ribulose? (see picture on #26) A) A B) B C) C D) D D - correct answer ✔✔Which of the following are allosteric regulators of phosphofructokinase in bacteria? A) fructose-2,6-bisphosphate B) ADP C) phosphoenolpyruvate D) B and C E) all of the above C - correct answer ✔✔A culture of yeast grown under anaerobic conditions is exposed to oxygen, resulting in a dramatic decrease in glucose consumption by the cells. How would the [NADH]/[NAD+] and [ATP]/[ADP] ratios change? A) Neither ratio will change B) Both ratios will decrease C) Both ratios will increase D) Only the [NADH]/[NAD+] ratio increases E) Only the [ATP]/[ADP] ratio increases D - correct answer ✔✔What is the net energetic cost of converting two pyruvate molecules to one glucose by gluconeogenesis, in ATP equivalents? A) 4 B) 8 C) 2 D) 6 C - correct answer ✔✔Which of the following represents the preferred order of fuel mobilization in humans? A) Amino acids > fatty acids > carbohydrates B) Carbohydrates > amino acids > fatty acids C) Carbohydrates > fatty acids > amino acids D) Fatty acids > carbohydrates > amino acids D - correct answer ✔✔Both glycogen synthesis and glycogen breakdown share the metabolite ______. A) gluconeogenesis B) glucose-6-phosphatase C) biotin D) glucose-1-phosphate E) dolichol B - correct answer ✔✔What would be the effect of acetyl-CoA on the activity of pyruvate carboxylase, which converts pyruvate to oxaloacetate? A) Inhibition B) Activation C) No effect D - correct answer ✔✔The regulated enzymes of the citric acid cycle include _____ . A) Malate dehydrogenase B) Fumarase E) cholesterol esters A - correct answer ✔✔The reaction catalyzed by the enzyme aldolase has a ΔG°' ≈ +23 kJ/mol. In muscle cells, the reaction proceeds in this same, forward direction. How can this occur? A) The concentration of substrate (s) must be significantly greater than that of product(s) in cells. B) The concentration of product(s) must be significantly greater than that of reactant(s) in cells. C) This ΔG°' means it is thermodynamically favored. D) The enzyme changes the ΔG of the reaction in cells to something favorable. B - correct answer ✔✔In which form of the β subunit do the substrates ADP + Pi bind? A) Open form B) Loose form C) Tight form E - correct answer ✔✔Berberi is a disease that results from a dietary lack of thiamine, the vitamin that serves as a precursor for thiamine pyrophosphate (TPP). Which metabolite(s) accumulate in individuals with beriberi, especially after ingestion of glucose? A) pyruvate B) NADH C) α-ketoglutarate D) A and B E) A and C A - correct answer ✔✔Given that the standard reduction potential of oxaloacetate is -0.166 V and the standard reduction potential of NAD+ is -0.315 V. What is the ΔE°' for the oxidation of malate by NAD+: Malate + NAD+→Oxaloacetate + NADH + H+ A) -0.149 V B) -4.81 V C) +0.149 V D) +0.0523 V E) + 4.81 V B - correct answer ✔✔Nigericin is an antibiotic that integrates into membranes and functions as a K+/H+ antiporter. Another antibiotic, valinomycin is similar, but it allows the passage of K+ ions. Given below is a diagram of a mitochondrion in which both antibiotics have integrated into the inner mitochondrial membrane. What happenes to ATP synthesis? (see picture on #45) A) ATP synthesis is unaffected B) ATP synthesis stops C) ATP synthesis increases A - correct answer ✔✔What would be the predicted energy yield of ATP from glycolysis in a patient with a defect in triosephosphate isomerase? A) 0 ATP B) 1 ATP C) 2 ATP D) 3 ATP E) 4 ATP E - correct answer ✔✔Administration of high concentrations of oxygen (hyperoxia) is effective in the treatment of lung injuries but can also be quite damaging. Due to decreased activity of lung aconitase the levels of citrate ______ and the levels of other TCA intermediates ______. This leads to a _______ level of glycolysis. A) decrease; increase; higher B) increase; increase; lower C) decrease; decrease; higher D) decrease; increase; lower E) increase; decrease; higher A - correct answer ✔✔How many protons could theoretically be pumped (under standard state conditions) by Complex III per mol of CoQ oxidized, considering the following information? coenzyme Q + 2H+ + 2 e- → coenzyme QH2 Eo' ≈ 0.040 V cytochrome c (Fe3+) + e- → cytochrome c (Fe2+) Eo' ≈ 0.270 V H+ (outside mt) → H+ (inside mt) ΔG ≈ -20kJ/mol A) ≤ 4 B) 4 < H+≤ 6 C) 6 < H+≤ 8 D) 8 < H+ E) Cannot be determined from the information provided. C - correct answer ✔✔Indicate whether Quinones occur in chloroplasts, mitochondria, or both: A) chloroplasts B) mitochondria C) both B - correct answer ✔✔Fructose-6-phosphate and ______ are used to make sucrose. A) ADP-glucose B) UDP-glucose C) UDP-galactose B - correct answer ✔✔Protons accumulate on the ____ side of the thylakoid membrane. A) stromal B) lumenal C) matrix D) cytosolic B - correct answer ✔✔The light harvesting complex is arranged so that photoreceptors that absorb photons with the shortest wavelengths are A) Closest to the reaction center chlorophyll D - correct answer ✔✔All transaminases require the cofactor A) thiamine pyrophosphate B) FAD C) NAD+ D) pyridoxyl-5'-phosphate E) lipoamide D - correct answer ✔✔The immediate precursor to AMP and GMP is ______. A) UMP B) CMP C) PRPP D) IMP E) ribose-5-phosphate B - correct answer ✔✔Which of the following is NOT an aspect of Photosystem II?A) Electrons from PSII are passed to plastoquinone. B) PSII oxidizes 2 H2O to produce 1 O2 involving 2 photooxidations. C) The reaction center chlorophyll absorbs a wavelength of 680 nm. D) A manganese catalyst extracts electrons from water. E) All of the above are true. C - correct answer ✔✔Cytochrome b6f is most similar to mitochondrial _____ with the exception that electrons are passed to _____, not to cytochrome c. A) complex I; plastocyanin B) complex I; plastoquinone C) complex III; plastocyanin D) complex III; plastoquinone E) none of the mitochondrial complexes are similar to cytochrome b6f E - correct answer ✔✔Why is photosystem I unable to oxidize water? A) it cannot transfer protons to the stroma B) it contains proteins that prevent oxygen from binding to it C) its reduction potential is exactly equal to that of oxygen D) it is a very good reducing agent E) it is not a strong enough oxidizing agent A - correct answer ✔✔Light dependent ATP production is called _____ and occurs in the _____ of chloroplasts. A) photophosphorylation; thylakoid membrane B) photophosphorylation; inner membrane C) non-oxidative phosphorylation; thylakoid membrane D) non-oxidative phosphorylation; inner membrane E) chloroplast-associated phosphorylation; thylakoid membrane B - correct answer ✔✔Complete the following reaction: P680 + light → _____ → _____ A) P680*; P680- + H+ B) P680*; P680+ + e- C) P680-; P680* D) P680+; P680* E) none of the above B - correct answer ✔✔Electrons are transferred from P680 to _____, then to cytochrome b6f. A) ubiquinone B) plastoquinone C) plastocyanin D) P700 E) NADP+ B - correct answer ✔✔Which of the following represents the correct order of steps in the RuBisCO reaction? i. enediolate intermediate attacks CO2 ii. splitting of molecule results in 2 molecules of 3-phosphoglycerate iii. enzyme removes H+ from C3 of ribulose-1,5-bisphosphate iv. hydroxyl group is added to C3 v. O atom of H2O attacks C3 A) i, ii, iv, v, iii B) iii, i, v, iv, ii C) ii, iv, v, iii, i D) iii, i, ii, iv, v E) iii, v, i, ii, iv C - correct answer ✔✔How many photons will be involved in the transfer of 4 electrons from PSII to 2 NADP+? A) 4 B) 2 C) 8 D) 6 C - correct answer ✔✔How many molecules of glyceraldehyde-3-phosphate are needed to generate 3 molecules of ribulose bisphosphate in the Calvin cycle? A) 3 B) 6 C) 5 D) 10 E) 4 B - correct answer ✔✔Which of the following statements about the Oxygen Evolving Center (OEC) is FALSE? A) It is located at the lumenal surface.