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BC 351- Unit 4
| Question | Answer |
|---|---|
| 3 steps that are different in gluconeogenesis | hexokinase, PFK, pyruvate kinase |
| hexokinase bypass in gluconeogenesis | glucose-6 phosphatase |
| PFK bypass in gluconeogenesis | fructose 1,6 biphosphatase 1 |
| pyruvate kinase bypass in gluconeogenesis | pyruvate carboxylase + PEP carboxykinase |
| 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 |
| regulation of enzyme activity | can affect Km or Vmax or both of the enzyme |
| heteroallostery | second, non substrate effector |
| In resting muscle cells the regulatory molecule that would accumulate and the enzyme that would be more active are | ATP and glycogen synthase |
| ATP and CTP regulate aspartate transcarbamoylase (ATCase) | by binding the R subunit and stabilizing ATCase in the R and T states, respectively. |
| A mechanism not used by cells to regulate enzyme activities is | substrate diffusion rate control. |
| 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 |
| 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 |
| Regulation of enzyme activity | often is found to integrate several types of signals |
| 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 |
| catabolic | produce ATP & NADH, shut off by high [ATP], activated by low [ATP] |
| anabolic | use ATP and NADH, shut off by low [ATP], activated by high [ATP] |
| Regulation of metabolic pathways | occurs through modulating the activity of paired enzymes catalyzing |
| 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 |
| The plot of the effect of ATP and AMP on PFK-1 activity indicates | ATP is a substrate and inhibitor |
| F2,6bisP | regulates Phosphofructokinase-1 (PFK-1) and Fructose 1,6 BisPhosphatase (F1,6 BisPtse) allosterically (step 3 bypass reactions) *inhibits gluconeogenesis |
| F2,6bisP is a ____ on PFK-1 | heteroallosteric activator |
| PKA is activated by | cAMP (will activate gluconeogenesis) |
| Regulation of glycolysis and gluconeogenesis in the liver | functions to stabilize the glucose levels in the blood through glucagon activation of PKA activity. |
| When the glucagon concentration in the blood increases the enzymatic activity decreases for | PhosphoFructoKinase-2. |
| each turn of CAC produces | 3 NADH, 1 FADH2, 1 GTP |
| 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. |
| 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 |
| 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. |
| 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 |
| Anaplerotic reactions | produce oxaloacetate and malate to maintain constant levels of citric acid cycle intermediates |
| The growth of nonphotosynthetic bacteria, but not animal cells, can occur on the carbon source | fatty acids |
| 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 |
| aerobic respiration | arose as an adaptation to increasing levels of oxygen in the atmosphere that had been produced by photosynthesis |
| matrix pH | 8 |
| intermembrane space pH | 7 |
| order of ETC | 1, 2, Q, 3, Cyt C, 4 |
| complex 1 ETC | NADH is used |
| complex 2 ETC | FADH2 is used |
| ubiquinone/ co Q carries | H+ and electrons |
| cytochromes carry | electrons only (redox potential depends on environment) |
| iron-sulfur proteins carry | electrons only (redox potential depends on environment) |
| mitochondrial electron carriers with the highest redox potential generally contain | copper or heme groups |
| 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 |
| 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. |
| 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 |
| 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 |
| 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 |
| The coupling of electron transport to ATP synthesis is likely to be affected in all of these systems by | dinitrophenol (carries protons across membranes) |
| 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 |
| ATP synthase works through | conformational changes causing an increase in the affinity for ATP and a decrease in affinity for ADP and Pi |
| Each complete rotation of the actin filament in ATP synthase requires | hydrolysis of 3 ATP |
| 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 |
| 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 |
| 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 |
| Allosteric enzymes | usually have more than one polypeptide chain. |
| Phosphofructokinase-2 and fructose 2,6 bisphosphatase are regulated in their relative activities by | phosphorylation by PKA |
| 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. |
| Cells oxidizing acetyl groups through the TCA cycle require molecular oxygen for | regeneration of NAD+ |
| Entry of acetyl-CoA into the citric acid cycle is decreased when | the ratio of [ATP]/[ADP] is high. |
| 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 |
| 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 |
| The electrochemical gradient produced by the electron transport chain | is referred to as proton motive force, pmf, or ΔP |
| ATP synthase is described as | a molecular motor |
| The mitochondrial ATP synthase | uses the energy stored in the proton gradient to drive conformational changes in the F1 component β subunit (ATP synthase) |
| complex 2 is also | an enzyme in CAC |
| chemiosmotic model | proton gradient couples ETC to ATP synthase production of ATP |
| heteroallosteric enzyme regulation | describes the mechanism of feedback inhibition of aspartate transcarbamoylase by CTP |
| regulation of glycolysis and gluconeogenesis in the liver | functions to stabilize glucose levels in blood thru glucagon regulation of PKA activity |
| Cells oxidizing acetyl groups through the TCA cycle require molecular oxygen for | regeneration of NAD+ |
| 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. |
| Evidence supporting the chemiosmotic theory | is exemplified by a higher MIM internal H+ concentration being sufficient for ATP synthesis |
| The F0 component of the F0F1-ATP synthase | serves as a proton channel |
| F1 component | ATPase/ATP synthase |
| low blood glucose-> | glucagon produced, PKA activated, phosphorylate PFK2/FBP2 (levels lowered), increased gluconeogenesis |
| what reaction accounts for most oxygen consumption? | transfer of electrons from cytochrome c to O2 |
Created by:
melaniebeale