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41 Cards in this Set
- Front
- Back
What is the complete aerobic respiration of glucose reaction? |
C16H12O2 + 6 O2 --> 6 CO2 + 6 H2O + energy |
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How do the products of the citric acid cycle contribute to the proton gradient? |
NADH and FADH2 generated from the TCA cycle are used by Complex 1 and 2 to pump protons |
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How is a voltaic cell set us to find reduction potential? |
Solution 1 = 1 M X + 1 M X- Solution 2 = 1 M H+ in equilibrium with 1atm H2 gas Connect with salt bridge and voltmeter |
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In a voltaic cell, if test solution takes electrons from the standard solution, the reduction potential is (positive/negative)? |
Positive |
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How do we mathematically calculate free energy of redox reaction? |
Standard free energy change = -nF(reduction potential) n = number of ions passing F = faraday constant in mol*V |
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Explain the flow of electrons through the ETC from NADH |
NADH --> NADH-Q reductase --> Ub --> Cytochrome c reductase complex --> cytochrome c --> cytochrome c oxidase complex --> O2 |
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Define cytochrome |
Protein with a heme cofactor |
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What is the full name of complex I? What is its net reaction? |
NADH-Q Oxidoreductase aka NADH dehydrogenase NADH + Q + 5 H+ matrix --> NAD+ + QH2 + 4 H+ cytoplasm Net pumping of 1 proton into matrix |
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How do electrons flow from NADH to Ubiquinone? |
Via complex I 1) NADH + FMN --> NAD+ + FMNH2 2) Through 2Fe-2S and 4Fe-4S clusters and to the Q pool |
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Explain the proton pumping in NADH-Q oxidoreductase |
As e- flow through clusters, 4 H+ are pumped into the intermembrane space from matrix and 2 H+ get taken up from matrix to reduce Q |
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What is the full name of complex II? What does it do? Does it pump protons? |
Succinate dehydrogenase Takes FADH2's electrons, shuttles them through iron-sulfur complexes, and reduce Q to QH2 Does not pump protons |
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What is the full name of Complex III? What does it do? How many protons does it pump? |
Coenzyme Q: Cytochrome c reductase Transfers e- from ubiquinol (QH2) to cyt c through a His-coordinated Fe-S cluster and heme. Pumps 2 protons into the intermembrane space |
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Describe the Q cycle that takes place in complex III |
1) QH2's electrons are transferred to Cyt C and Oxidized Q one at a time forming Cyt C1 and quinone radical with pumping of 2 protons 2) Step 1 repeats with generation of QH2 from quinone radical and Cyt C from cyt c1 with pumping of 2 more protons |
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What is the full name of complex IV? What does it do? |
Cytochrome C oxidase transfers electrons from cytochrome c to O2 to make water |
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Describe the flow of electrons through complex IV from cytochrome C to water |
2 Cytochrome c (4 e-) --> Cu A motif --> heme a --> heme a3 (one e- pair stops here) --> Cu 8 (another e- pair stops here) --> H2O |
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Why are there two heme a's? |
They have the same heme group but distinct redox potentials due to their different protein environments |
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Cytochrome C oxidase contains __ copper atoms coordinated to _____ side chains |
3 copper atoms coordinated to histidine sidechains |
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How do we make water from reducing heme a3 and Cu 8? |
Once reduced, O2 acts as a bridge forming a heme (a3)-O-O-(Cu 8) peroxide bridge. The RO-OR' bond gets reduced initially to OH by 2 protons, then to two H2O by 2 more protons from the matrix |
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What complex is most likely to produce ROS? What enzymes protect from ROS damage? |
Complex I Superoxide dismutase and catalase |
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How does superoxide dismutase do? |
E reduced + Radical O2 + 2 H+ --> H2O2 + E oxidized |
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How does Catalase do? |
Catalse finishes the half assed job superoxide dismutase did. 2 H2O2 --> O2 + 2 H2O |
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How does cyanide work and where in the ETC does it work? |
Cyanide binds ferric heme which is found in complex III and IV |
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What does F0 F1 mean? |
F0 is the membrane bound proton conducting stick subunit F1 is the matrix side ball subunit with ATPase activity |
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What is the role of the proton gradient in ATPase? |
To release ATP from the synthase since ATP cannot leave the active site unless protons flow through the enzyme. Movement through the half-channels from a proton rich to a proton poor environment powers rotation of the c-ring |
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Describve the structure of the c-ring |
3 alpha and 3 beta subunits arranged alternatively in a hexameric ring P-loop NTPase members gamma subunit in middle Each member of the ring interacts with a different face of the gamma subunit |
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Describe the O, T, and L sites of the c-ring |
O = Open: Product release and substrate binding ADP + Pi L = Loose: ADP + Pi trapping T = Catalysis ATP <-> ADP + Pi |
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The gamma subunit rotates (degrees?) (clockwise/counterclock wise?) during ATP synthesis when viewed down the gamma subunit |
120 degrees counterclockwise |
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Describe proton flow through ATPase |
1) Cytoplasmic protons enter half-channels (a subunit) where they interact with an Asp on the c subunit 2) Protonation of the Asp allows it to move through the hydrophobic environment of the membrane until it reaches a proton poor envrionment where the Asp is deprotonated |
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How many proton drive 1 revolution of the ATPase? How many ATP do we generate per revolution? How many protons per ATP does that make it/ |
10 protons per revolution 3 ATP/revolution 3.33 protons flow into the matrix/ATP |
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What 2 pathways allow us to regenerate NAD+ in the cytoplasm? |
1) Glycerol-3-phosphate shuttle 2) Malate-Aspartate shuttle |
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Describe the glycerol 3-phosphate shuttle mechanism. Where would we expect to see this mechanism occur? |
1) NADH reduces DHAP to form Glycerol 3-phosphate 2) Glycerol 3-phosphate is oxidized by FAD to FADH2 3) FADH2 reduces Q to QH2 which go to the Quinone pool Found in muscle due to ability to sustain high levels of oxidative phosphorylation |
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What enzymes catalyzes the entrance of cytoplasmic high-energy electrons into the ETC via the glycerol 3-phosphate shuttle? |
Glycerol 3-phosphate dehydrogenase catalyzes 2 reactions 1) NADH + DHAP <-> NAD+ + Glycerol 3-phosphate 2) FAD + Glycerol 3-phosphate <-> FADH2 + DHAP |
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Describe electron flow in the malate-aspartate shuttle |
1) NADH + Oxaloacetate <-> NAD+ + Malate in the cytoplasm 2) Malate is antiported with alpha-ketoglutarate and then oxidized by NAD+ in the matrix to form NADH + Oxaloacetate |
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How does the energy yield of NADH entering via the glycerol 3-phosphate shuttle differ from the energy yield of NADH entering via complex I? Why? Also what is complex I called? |
NADH entering via Glycerol 3-phosphate shuttle yields 1.5 ATP instead of 2.5 because FAD is the e- acceptor in complex I (NADH-Q oxidoreductase) enabling e- to flow against the NADH gradient |
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What is the purpose of transaminating oxaloacetete to alpha-ketoglutarate once it has been formed by the oxidation of malate by NAD+ in the malate-shuttle? |
Alpha-ketoglutarate is then used to fuel the antiport of malate into the matrix by coupling the favorable alpha-ketoglutarate gradient to the unfavorable malate gradient |
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What is the role of glutamate and aspartate in the malate shuttle? |
Glutamate donates an amino to oxaloacetate. Glutamate's deamination yields aspartate, and oxaloacetate's amination yields alpha-ketoglutarate. The favorable aspartate gradient is then used to antiport against the unfavorable glutamate gradient. |
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How does the role of glutamate and aspartate in the malate shuttle differ in the cytoplasm and matrix? |
In the cytoplasm, Asparate deaminates alpha-ketoglutarate to regenerate glutamate The the matrix, Aspartate is used to couple antiport of glutamate into the matrix Cytoplasmic glutamate is amino acceptor (cytoplasm) and donor (matrix) |
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The glycerol 3-phosphate shuttle can take the place of ____ _____ to provide NAD+ in muscle |
Take place of lactate dehydrogenase |
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What are the component of the ATP Synthasome? |
1) ATP-ADP translocase 2) F0F1 ATP synthase 3) Protons 4) Phosphate Carrier |
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How many ATP are net yielded from the complete oxidation of glucose? How many does glycolysis, citric acid cycle, and oxidative phosphorylation yield respectively? |
30 Glucose/ complete oxidation 2 from Glycolysis 2 from Citric Acid cycle 26 from Oxidative phosphorylation |
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How many high energy electrons are yielded from the complete oxidation of glucose? How many does glycolysis, citric acid cycle, and oxidative phosphorylation yield respectively? e |
2 NADH in glycolysis 2 NADH in the conversion of Pyruvate to Acetyl CoA 6 NADH + 2 FADH2 in the Citric Acid Cycle 2 NADH Oxidative phosphorylation 12 NADH + 2 FADH2 in complete oxdiation of glucose |