Biochem Study Guide 3

What is the net ATP yield per glucose molecule at the end of the glycolytic pathway?
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Under anaerobic conditions, skeletal muscle generates lactate from pyruvate. Why does it do this?To regenerate NAD+ for further glycolysisWhich of the following two enzymes catalyze the two oxidation-reduction reactions in the fermentation of alcohol from glucose?Glyceraldehyde-3-Phosphate Dehydrogenase and Alcohol DehydrogenaseWhat happens to lactate after it is produced by anaerobic muscle tissue?It is carried by the blood to the liver for gluconeogenesis back to glycogen.Which of the following enzymes catalyzes a reversible reaction that is an equilibrium-controlled step of glycolysis?Pyruvate KinaseSeven of the 10 reactions of glycolysis are reversible (ΔG near zero) and can be used in reverse of glycolysis for gluconeogenesis. Which enzymes catalyze the three irreversible reactions?Hexokinase, Phosphofructokinase-1, Pyruvate KinaseWhich of the following enzymes converts UDP-galactose to UDP-glucose?UDP-Glucose-4-EpimeraseWhich of the following enzymes may cause galactosemia to disappear in adults due to its metabolism of galactose-1-phosphate?UDP-Glucose PyrophosphorylaseWhere does glycerol generated by hydrolysis of triacylglycerols enter glycolysis?At the dihydroxyacetone phosphate stageWhich carbon molecule enters the TCA cycle and exits as CO2, with metabolic energy captured as ATP, NADH, and [FADH2]?Acetyl-CoAWhere do glycolysis and the TCA cycle, respectively, occur in eukaryotic cells?Cytoplasm; MitochondriaWhich enzyme catalyzes the decarboxylation of pyruvate to acetyl-CoA?Pyruvate Dehydrogenase ComplexThe pyruvate dehydrogenase complex contains 3 multimeric enzymes. Which of the following is NOT a property of the complex?It binds NAD+ in its active site.Which molecule is an allosteric inhibitor of citrate synthase?NADHWhich enzymes of the TCA cycle catalyze oxidative decarboxylation reactions?Isocitrate Dehydrogenase and α-Ketoglutarate DehydrogenaseWhich of the following is NOT part of the 2-step reaction catalyzed by isocitrate dehydrogenase?oxidation of the C-2 alcohol of isocitrate to form oxalosuccinateWhich of these enzymes catalyzes the only reaction of the citric acid cycle that provides substrate-level phosphorylation?Succinyl-CoA synthetaseEnergy is derived from the succinate dehydrogenase mechanism. What process is the energy used for?reduction of [FAD]Which of the following is NOT a characteristic of the oxidation of malate to oxaloacetate (OAA)?It is very exergonic.How many NADH molecules are produced in the TCA cycle per molecule of acetyl-CoA oxidized?3What are the anaplerotic reactions associated with the TCA cycle a result of?The use of many of the TCA cycle intermediates in biosynthesis.Which enzyme is allosterically activated when acetyl-CoA levels exceed oxaloacetate (OAA) supply?Pyruvate CarboxylaseWhich of the following is NOT correct for pyruvate carboxylase?It resides in mitochondria of plants, but not animals.Why is it crucial that regulation occurs at pyruvate dehydrogenase?The product acetyl-CoA is committed to oxidation in the citric acid cycle or fatty acid biosynthesis.Which enzyme phosphorylates mammalian pyruvate dehydrogenase and is allosterically activated by high levels of NADH and acetyl CoA?Pyruvate dehydrogenase kinaseWhich of the following allosterically stimulate mammalian isocitrate dehydrogenase?High NAD+/NADH and high ADP/ATP ratiosWhich of the following is an essential feature of the glyoxylate cycle that is NOT associated with the TCA cycle?It utilizes condensation of acetyl-CoA with succinate.Which of the following is NOT correct for the glyoxylate pathway?Glyoxysomes contain all the enzymes for the glyoxylate cycle.Which molecules are generated when isocitrate lyase cleaves isocitrate?Succinate and GlyoxylateWhich of the following resides in the mitochondria?The electron transport complexesWhich of the following is the common product produced by Complex I and Complex II?Reduced coenzyme QWhich of the following is another term used to define Complex II in the electron-transport chain?Succinate-CoQ reductaseWhich of the following cytochromes receives the electron transferred from UQH2 to the Rieske protein?cyt c1Which of the following is the source for the energy that drives ATP synthesis?The proton gradientWhich of the following is a characteristic of the F1 unit of ATP synthase?The β-subunits have catalytic sites for ATP synthesis.Which of the following c-subunit residues of ATP synthase is proton neutralized during ATP synthesis?AspWhich of the following defines the P/O ratio?Molecules of ATP formed per 2 electrons flowing through electron-transport chainWhich of the following is a characteristic of the malate-aspartate?Electrons of cytosolic NADH are translocated to mitochondrial NADH.Which of the following statements is a characteristic of the glycerophosphate shuttle?It shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1.5 ATP/NADH.Which of the following is NOT correct regarding the glycerophosphate shuttle?Glycerol-3-phosphate is translocated across the inner mitochondrial membrane into the matrix.Which of the following is a part of apoptosis?Mitochondrial Membrane Permeabilization (MMP)In which of the following organelles does photosynthesis take place?ChloroplastsWhich of the following structures is formed in chloroplasts when the thylakoid membrane is organized into paired folds?LamellaeWhich of the following explains how chloroplasts differ from mitochondria?In chloroplasts, the proton gradient is generated between the thylakoid lumen and the stroma.Which of the following are the primary roles of carotenoids in photosynthesis?Accessory light harvesting and Photoprotection from reactive oxygen speciesWhen light energy is absorbed by chlorophyll, an electron is promoted to a higher orbital and then transferred to a suitable acceptor, resulting in light energy conversion to chemical energy. Which of the following terms describes this type of reaction?Oxidation-reductionWhich of the following represents the molecules of A and B in the reaction sequence below? Chl + hv → Chl* Chl* + A → Chl.+ + A- Chl.+ + A- → Chl.+ + B+Electron-transferWhere do electrons from water ultimately flow to, via PSI and PSII?NADP+Which of the following is NOT a property of photosystem II (PSII)?Light-driven H2O evolutionWhich of the following is a property of both the P700 and the P680 reaction centres?Activated by visible lightWhich of the following is the product(s) of the R. viridis photosynthetic reaction centre?Mobile reduced quinoneWhich of the following is the equivalent of product formed, as defined by the quantum yield of photosynthesis?Light inputWhich of the following statements regarding light is correct?The energy of 700 nm light is greater than that of 400 nm light.Which of the following terms defines photophosphorylation?ATP synthesis driven by light energyWhich of the following two components constitute the proton-motive force?A membrane potential and a pH gradientWhich of the following describes when does cyclic photophosphorylation take place?When the NADPH/ NADP+ ratio is high and energy is used in generating ATPWhich of the following components are produced in the light reactions of photosynthesis and are used to convert carbon dioxide to sugar?ATP and NADP+Which of the following does NOT contribute to the activation of rubisco?Zn2+ bindingWhich of the following statements regarding the enzyme rubisco is correct?Its catalytic site has both carboxylase and oxygenase activity.Which of the following describes how photorespiration avoided in C-4 plants?Carbon dioxide transportation from the mesophyll cells to the bundle sheath cellsWhich of the following is NOT a characteristic of a C-4 plant?Carbon dioxide uptake in the daytime and fixation at nightWhich of the following essential enzymes in C-4 plants is used to conserve CO2 and avoid photophosphorylation?PEP carboxylaseWhat is synthesized in gluconeogenesis?Glucose from non-carbohydrate precursorsWhich of the following is NOT a substrate for gluconeogenesis?AcetateWhich major tissues carry out gluconeogenesis?Liver and KidneysWhich tandem enzyme controls the cellular levels of fructose-2,6-bisphosphate (F-2,6-BP)?F-2,6-BPase and PFK-2cAMP-dependent protein kinase phosphorylates and thus inhibits PFK-2. Which enzyme is simultaneously activated as a result of this inhibition?F-2,6-BPaseWhat is the primary regulatory point of gluconeogenesis?Fructose-1,6-bisphosphataseWhich of the following is NOT correct for α-amylase?It catalyzes hydrolysis of α(1→ 6 ) linkages in amylopectin.Limit dextrins are degraded by the action of a debranching enzyme that has 2 distinct enzymatic activities. Which enzymatic activities does it carry out?oligo(α1,4 → α1,4)glucanotransferase; α(1→ 6)glucosidaseWhich of the following enzyme-catalyzed steps requires energy input for the synthesis of glycogen?UDP-glucose pyrophosphorylaseWhere is glucose from UDP-glucose transferred to so that the initiation of glycogen synthesis occurs?To the tyrosine-OH group of glycogeninWhich 2 enzymes must be carefully controlled in glycogen synthesis and degradation in order to properly serve the metabolic needs of the organism?Glycogen phosphorylase and Glycogen synthaseInsulin in the bloodstream is a response to increased blood glucose. What does insulin do as a result of this?Stimulates glycogen synthesis in muscle and liverEpinephrine elicits many physiological changes such as the initiation of the adenylyl cyclase cascade. Which of these actions is NOT seen as a result of this initiation?Stimulation of glycogen synthaseWhich process describes the 6-phosphogluconate dehydrogenase reaction?Oxidative decarboxylationWhich enzyme-catalyzed reaction is analogous to the phosphopentose isomerase reaction and mechanism?PhosphoglucoisomeraseIf NADPH is needed for biosynthetic reactions but ribose-5-P is not needed, which of the following best represents the net reaction of the pentose phosphate pathway?3 gluc-6-P + 6 NADP+ → 6 NADPH + 3 CO2 + 2 fruc-6-P + 1 glyceraldehyde-3-PComplex Itransports protons from the matrix to the cytosolComplex IIoxidizes succinate and reduces coenzyme QComplex IIImediates electron transport from coenzyme Q to Cytochrome cComplex IVtransfers electrons from cytochrome c to reduce oxygen on the matrix side