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43 Cards in this Set
- Front
- Back
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During what steps of the TCA cycle is a large amount of free energy released?
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Steps 1,3,4.
1) AcCoA --> Citrate 3) Isocitrate --> alpha-Ketoglutarate 4) alpha-Ketoglutarate --> Succinyl CoA |
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During what steps of the TCA cycle are energy-producing products released? What is released during each?
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Steps 3,4,5,6,8
3) NADH 4) NADH 5) GTP 6) FAD2H 8) NADH |
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What else besides isocitrate (in the TCA cycle) can provide alpha-ketoglutarate?
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Amino acids
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What else besides alpha-ketoglutarate (in the TCA cycle) can provide succinyl CoA?
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-Odd chain fatty acids
-Valine -Isoleucine |
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What else besides succinate (in the TCA cycle) can provide fumarate?
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Amino acids
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What else besides malate (in the TCA cycle) can provide oxaloacetate?
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Aspartate
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What has the smell of almonds?
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HCN! (Cyanide)
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What are the names of the four protein complexes that make up the electron transport chain?
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I. NADH Dehydrogenase
III. Cytochrome C reductase IV. Cytochrome oxidase V. ATP synthase (F1F0ATPase) |
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What function do Q and C have in oxidative phosphorylation?
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They are mobile carriers of electrons between the protein complexes. QH2 carries electrons between I and III and C carries electrons between III and IV.
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What is the electrochemical potential called that drives oxphos?
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Proton motive force. This is composed of a chemical gradient (high concentration of H+ pumped outside the cell) as well as a transmembrane electrical gradient. Both are forces into the cell that drive the ATPase.
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What are 3 processes that occur within the mitochondrial matrix? What structures are found within the matrix?
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-TCA cycle, pyruvate oxidation, FA oxidation
-Ribosomes, RNA, DNA |
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What is the one TCA cycle enzyme that is NOT found in the inner mitochondrial membrane? Where is it? Why?
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-Succinate dehydrogenase
-Bound to the inner mito membrane -Participates in ox phos as well as TCA cycle. Known as complex II. |
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How many H+ ions are pumped out per FADH? Per NADH?
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FADH=6
NADH=10 ATP synthesis requires 4H+/ATP so that's why you get 1.5ATP/FADH2 and 2.5ATP/NADH! |
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What does -enol mean?
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-Has an alcohol (may be OP instead of OH) and an "alkene" (double bond).
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After ATP is created in the mitochondria, how does it get out into the cell to do its good things? Conversely, how does ADP get back into the inner mito membrane? What kind of transport is this?
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There is an adenine nucleotide transporter in the membrane of the inner cell membrane. It is an antiporter.
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In the ETC, what does complex 2 do?
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Complex 2 (succinate dehydrogenase) oxidizes FAD2H to FAD, reducing Q to QH2. Complex 2 does not pump H+!
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In the ETC, what does complex 1 do?
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Complex 1 oxidizes NADH and H+ to NAD+. This pumps 4 H+ into the space between the mito membranes.
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In the ETC, what does complex 3 do?
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Complex 3 takes electrons from complex 1 (in the form of QH2) by oxidizing Q2H to Q again. This pumps 4 electrons out into the space between the mito membranes.
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In the ETC, what does complex 4 do?
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Complex 4 takes electrons from complex 3 in the form of C. It creates water from 2H+ and 1/2 O2 and pumps 2 protons out into the space between the mito membranes.
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Why does FAD2H produce less ATP than NADH?
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FAD2H only goes through protein complex 2 (no protons pumped!), 3 (4 protons pumped), and 4 (2 protons pumped) for a total of 6 protons pumped out. NADH goes through 1,3,4 which pumps a total of 10 electrons.
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What is special about the progression of NADH to CoQ to C to O2?
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Each one of these transfers of electrons have enough energy to create ATP.
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Of the protein complexes involved in ETC, which one is made entirely of subunits encoded for by nuclear DNA?
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Complex II, succinate dehydrogenase.
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What are 5 components of the ETC that are proteinaceous?
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Complexes I-IV and cytochrome C.
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What are 5 components of the ETC that are non-proteinaceous?
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Flavin, Fe, Quinone (Q), Heme, and Copper
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What happens in Leber hereditary optic neuropathy?
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LHON is a disease of the ETC. Usually a point mutation in the mtDNA encoding for Complex I. OxPhos diseases often manifest with neuro or ophthal sxs because have a high demand for energy.
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What does heteroplasmy refer to?
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Mixture of wild type and mutated forms.
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Why are mutations more common in mtDNA?
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-Hazard of the job (oxygen free radicals produced by mitochondria)
-No repair mechanisms! |
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What do cytochrome do?
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Heme containing, involved in electron transport.
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How can you tell if there's FAD or FMN?
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FAD and FMN are yellow
FAD and FMN (partially oxidized) are red or blue. FAD2H is colorless. |
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What are iron sulfur centers good at?
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Great for shuttling electrons!
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How can you tell if you have an oxidized or reduced iron sulfate centers?
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When oxidized, they're brown, when reduced, they fade in color.
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How can you tell if you have any kind of heme?
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It's red...
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Why doesn't heme in cytochrome bind oxygen?
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Ligands are blocking the binding site.
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Where does CN bind to mess up OxPhos?
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CN binds to cytochrome C in complex IV. This is the only cytochrome that is able to bind to oxygen (recall that the other cytochromes have their oxygen binding site blocked by ligands.)
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Rank in increasing order of affinity for oxygen:
myoglobin, hemeglobin, cytochrome. |
Hemoglobin, myoglobin, cytochrome
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What enzyme breaks down hydrogen peroxide?
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Catalase
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What enzyme breaks down superoxide?
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Superoxide dismutase
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What is the sequence of oxygen reduction? Start with O2 and go to H2O.
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O2 - O2 superoxide - H2O2 hydrogen peroxide - 2H2O water
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What is the most important factor in controlling how quickly oxygen is reduced in the ETC? What causes the slowdown?
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The presence of ADP is crucial to moving electrons through the ETC. Backpressure (pumping against the gradient) causes it to slow without ADP.
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How does dinitrophenol "uncouple" the ETC?
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Dinitrophenol picks up a proton outside of the inner mito membrane, crosses the membrane, and releases the proton. This causes the electrochemical to dissipate.
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What happens when the ETC is uncoupled?
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Fuel will be consumed but no ATP will be produced.
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What is the mechanism by which babies are able to stay warm without shivering?
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Babies have brown fat, which serves as an ETC uncoupler. Thermogenin is the protein that opens a pore that allows protons back in. Fuels are consumed, heat is produced instead of ATP.
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What are the 3 phases of the ATPase?
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Loose, tight, open
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