BC 351- Unit 4
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| 3 steps that are different in gluconeogenesis | hexokinase, PFK, pyruvate kinase
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| hexokinase bypass in gluconeogenesis | glucose-6 phosphatase
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| PFK bypass in gluconeogenesis | fructose 1,6 biphosphatase 1
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| pyruvate kinase bypass in gluconeogenesis | pyruvate carboxylase + PEP carboxykinase
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| Considering the role of ATP formation and hydrolysis in energy coupling of anabolic and catabolic pathways, what must be true? | high levels of ATP act as allosteric activators of anabolic pathways
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| regulation of enzyme activity | can affect Km or Vmax or both of the enzyme
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| heteroallostery | second, non substrate effector
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| In resting muscle cells the regulatory molecule that would accumulate and the enzyme that would be more active are | ATP and glycogen synthase
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| ATP and CTP regulate aspartate transcarbamoylase (ATCase) | by binding the R subunit and stabilizing ATCase in the R and T states, respectively.
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| A mechanism not used by cells to regulate enzyme activities is | substrate diffusion rate control.
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| enzymes have activity in the cell that varies continuously from very high to very low | because it is the activity of the population of enzyme
molecules that determines the cellular activity
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| You are studying an enzyme that has a 3-fold increase in KM, but no change in VMax upon phosphorylation... The best interpretation of your result is | your enzyme is positively regulated by a protein phosphatase
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| Regulation of enzyme activity | often is found to integrate several types of signals
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| For ATP hydrolysis, ATP ADP + Pi, what is the effect of changing the reaction conditions from standard chemical conditions to biochemical standard conditions (other than the ATP and ADP concentrations) on ΔG of the reaction? | The ΔG of the reaction will be more negative at a given ADP/ATP ratio
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| catabolic | produce ATP & NADH, shut off by high [ATP], activated by low [ATP]
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| anabolic | use ATP and NADH, shut off by low [ATP], activated by high [ATP]
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| Regulation of metabolic pathways | occurs through modulating the activity of paired
enzymes catalyzing
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| Regulation of glycolysis vs. gluconeogenesis | is through the response of the key enzymes to indicators of energy charge in the cell like ATP and AMP
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| The plot of the effect of ATP and AMP on PFK-1 activity indicates | ATP is a substrate and inhibitor
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| F2,6bisP | regulates Phosphofructokinase-1 (PFK-1) and Fructose 1,6 BisPhosphatase (F1,6 BisPtse) allosterically (step 3 bypass reactions)
*inhibits gluconeogenesis
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| F2,6bisP is a ____ on PFK-1 | heteroallosteric activator
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| PKA is activated by | cAMP (will activate gluconeogenesis)
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| Regulation of glycolysis and gluconeogenesis in the liver | functions to stabilize the glucose levels in the blood through glucagon activation of PKA activity.
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| When the glucagon concentration in the blood increases the enzymatic activity decreases for | PhosphoFructoKinase-2.
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| each turn of CAC produces | 3 NADH, 1 FADH2, 1 GTP
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| A deficiency in the vitamin thiamine results in higher than normal levels of pyruvate and α- ketoglutarate in the blood suggesting that thiamine | is necessary for the function of specific dehydrogenases.
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| If citrate (C6H8O7) were completely oxidized to CO2 and H2O, the number of molecules of O2 consumed per molecule of citrate would be around A. 2. | 5
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| The reaction of the citric acid cycle that is most similar to the pyruvate dehydrogenase complex-catalyzed conversion of pyruvate to acetyl-CoA is the conversion of | α-ketoglutarate to succinyl-CoA.
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| The reaction of the citric acid cycle that produces an ATP equivalent (in the form of GTP) by substrate level phosphorylation is the conversion of | succinyl-CoA to succinate
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| Anaplerotic reactions | produce oxaloacetate and malate to maintain constant levels of citric acid cycle intermediates
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| The growth of nonphotosynthetic bacteria, but not animal cells, can occur on the carbon source | fatty acids
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| Citrate synthase and the NAD+- specific isocitrate dehydrogenase are two key regulatory enzymes of the citric acid cycle. These enzymes are inhibited by | ATP and/or NADH
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| aerobic respiration | arose as an adaptation to increasing levels of oxygen in the atmosphere that had been produced by photosynthesis
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| matrix pH | 8
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| intermembrane space pH | 7
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| order of ETC | 1, 2, Q, 3, Cyt C, 4
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| complex 1 ETC | NADH is used
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| complex 2 ETC | FADH2 is used
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| ubiquinone/ co Q carries | H+ and electrons
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| cytochromes carry | electrons only (redox potential depends on environment)
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| iron-sulfur proteins carry | electrons only (redox potential depends on environment)
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| mitochondrial electron carriers with the highest redox potential generally contain | copper or heme groups
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| Addition of reduced ubiquinone to mitochondria lacking cytochrome c would not produce a proton gradient because | ubiquinone cannot bind to cytochrome c oxidase (C IV) as required to pass electrons to it
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| The direct generation of a proton gradient by electron-transport proteins | requires that the oxidized and reduced states of the electron-transport protein have different conformations.
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| The coupled redox reaction with enough ΔG to synthesize one molecule of ATP from ADP and Pi under standard conditions is | the oxidation of cytochrome c by oxygen
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| Cotransport of protons from the intermembrane space to the matrix is required for | import of acetic acid ions into the matrix from the intermembrane space
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| The antibiotic bongkrekic acid inhibits the ATP/ADP transport protein across the inner mitochondrial membrane; to allow electron transport to occur in mitochondria treated with bongkrekic acid you can | permeabilize the inner membrane to protons
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| The coupling of electron transport to ATP synthesis is likely to be affected in all of these systems by | dinitrophenol (carries protons across membranes)
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| When the ΔG'° of the ATP synthesis reaction is measured on the surface of the ATP synthase enzyme, it is found to be close to zero. This is thought to be due to | stabilization of ATP relative to ADP by enzyme binding
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| ATP synthase works through | conformational changes causing an increase in the affinity for ATP and a decrease in affinity for ADP and Pi
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| Each complete rotation of the actin filament in ATP synthase requires | hydrolysis of 3 ATP
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| The conversion of 1 mol of fructose 1,6-bisphosphate to 2 mol of pyruvate by the glycolytic pathway results in a net formation of | 2 mol of NADH and 4 mol of ATP
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| During strenuous exercise, the NADH formed in the glyceraldehyde 3-phosphate dehydrogenase reaction in skeletal muscle must be reoxidized to NAD+ if glycolysis is to continue. The most important reaction involved in the reoxidation of NADH is | pyruvate → lactate
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| The anaerobic conversion of 1 mol of glucose to 2 mol of lactate by fermentation is accompanied by a net gain of | 2 mol of ATP
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| Allosteric enzymes | usually have more than one polypeptide chain.
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| Phosphofructokinase-2 and fructose 2,6 bisphosphatase are regulated in their relative activities by | phosphorylation by PKA
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| what is correct regarding the oxidative decarboxylation of pyruvate in aerobic conditions in animal cells? | One of the products of the reactions of the pyruvate dehydrogenase complex is a thioester of acetate.
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| Cells oxidizing acetyl groups through the TCA cycle require molecular oxygen for | regeneration of NAD+
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| Entry of acetyl-CoA into the citric acid cycle is decreased when | the ratio of [ATP]/[ADP] is high.
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| When a glucose molecule is broken down to CO2 in glycolysis and the TCA cycle, little ATP is directly produced, most of the energy is | stored as NADH
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| In the reoxidation of QH2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because | cytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor
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| The electrochemical gradient produced by the electron transport chain | is referred to as proton motive force, pmf, or ΔP
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| ATP synthase is described as | a molecular motor
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| The mitochondrial ATP synthase | uses the energy stored in the proton gradient to drive conformational changes in the F1 component β subunit (ATP synthase)
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| complex 2 is also | an enzyme in CAC
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| chemiosmotic model | proton gradient couples ETC to ATP synthase production of ATP
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| heteroallosteric enzyme regulation | describes the mechanism of feedback inhibition of aspartate transcarbamoylase by CTP
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| regulation of glycolysis and gluconeogenesis in the liver | functions to stabilize glucose levels in blood thru glucagon regulation of PKA activity
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| Cells oxidizing acetyl groups through the TCA cycle require molecular oxygen for | regeneration of NAD+
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| The electron transport chain | functions to couple the transfer of e-s from NADH and FADH2 to O2 to transport H+s out of the matrix against a concentration and charge gradient.
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| Evidence supporting the chemiosmotic theory | is exemplified by a higher MIM internal H+ concentration being sufficient for ATP synthesis
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| The F0 component of the F0F1-ATP synthase | serves as a proton channel
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| F1 component | ATPase/ATP synthase
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| low blood glucose-> | glucagon produced, PKA activated, phosphorylate PFK2/FBP2 (levels lowered), increased gluconeogenesis
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| what reaction accounts for most oxygen consumption? | transfer of electrons from cytochrome c to O2
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