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74 Cards in this Set
- Front
- Back
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Reduction is a _____ of electrons.
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Gain (OIL RIG)
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Oxidation is a _____ of electrons.
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Loss (OIL RIG)
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What is the standard half reaction for SRP?
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2H+ + 2e- <--> H2
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What does a negative E mean? Good oxidizing or good reducing agent?
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Good reducing agent!
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How does the SRP differ between standard and physiological conditions?
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pH 7, not pH 0
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What is the E value of the standard half-reaction at physiological conditions?
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E = - 0.421 V
(know that it is lower) |
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How do you calculate the change in SRP?
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∆E = E (e- acceptor) - E (e- donor)
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If the ∆E is negative, will the reaction be spontaneous? Why?
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Non-spontaneous
∆G = - nF∆E |
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Which equation would you use to calculate the SRP of reaction NOT under standard conditions? i.e. not 1:1 ratios of reductant and oxidant
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Nernst equation
∆E = ∆E˚ - (RT/nF)(ln ([Ared][Box+])/[Ared+][Box])) |
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Which compound donates its electrons to Complex I of the ETC?
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NADH
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What donates its electrons to Complex II of the ETC? Which enzyme creates this compound?
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FADH2
Succinyl dehydrogenase (CAC) |
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What is the total energy released by the full ETC reaction from NADH?
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218 kJ/mol
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Is the energy released from Complex II sufficient to produce ATP?
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No, only 16.4 kJ/mol are released
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How much energy is need to drive the following reaction reaction:
ADP + Pi --> ATP |
30.5 kJ/mol
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Why is the physiological efficiency of ATP synthesis coupled to the ETC only 70%?
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[H+] diffuse back to matrix without going through ATP synthase.
e.g. Pyruvate translocase |
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What are the inhibitors of the ETC complexes?
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Complex I --> Rotenone
Complex II -->Antimycin A Complex III --> Cyanide |
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Is ATP directly produced from the ETC?
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NO!!!!!!! ATP synthase is a COMPLETELY separate complex.
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How many ATP can be produced from the energy released by FADH2 oxidation? Why?
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2 ATP, since the electrons are released at complex II.
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How many ATP are produced from NADH oxidation?
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3 ATP
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What is the final electron recipient of the ETC? What is formed?
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Oxygen.
1/2 O2 + 2H+ ---> H2O |
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Why does the P/O ratio diminish with electron entry further down the ETC?
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Less oxidation steps occur and less free energy is released to drive the proton gradient.
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Is Cytochrome C mobile or immobile? Coenzyme Q?
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They are both mobile
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What is the active centre of cytochrome?
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Heme
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How many electrons can a heme handle at once?
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1 electron
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Does the SRP increase or decrease along the ETC?
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Increases
NADH --> NAD+ (-0.315 V) 1/2 O2 + 2H+ --> H2O (+0.815 V) |
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What are the three states of Coenzyme Q?
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Oxidized: Quinone
Partially reduced: Semiquinone Reduced: Hydroquinone |
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Name a role of Cytochrome C outside of the ETC.
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Apoptosis
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In which complexes are FeS clusters found?
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Complex I and III
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Where is cytochrome C located? In or on the membrane?
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On the membrane
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Can ATP synthase work in reverse? If yes, when?
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It can work in reverse when proton gradient is present.
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How does the ETC store energy? (This is a really easy question)
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Proton gradient in the IMS.
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Name the 5 points supporting chemiosomotic theory?
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- Oxphos needs intact membrane
- IMM impermeable to ions - ETC associated with proton transport out of matrix - reconstitution experiments - uncoupling agents increase permeability of IMM and stop ATP synthesis |
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What is the chemiosmotic theory?
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ATP synthesis requires a proton gradient created by pumping of protons from matrix to IMS.
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Which lipids make the IMM impermeable?
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Cardiolipins (comes from 2X PG)
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Name an uncoupling agent? Compound that increases permeability of IMM
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DNP or FCCP
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In what tissue does natural coupling occur? What is its utility?
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- Brown Fat Tissue
- Used in thermogenesis |
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Which hormone regulates natural uncoupling? What is its mechanism of action?
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Norepinephrine --> Adenylate cyclase --> cAMP --> PKA --> UCP1 --> thermogenin
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Which proton channel is opened in natural uncoupling? What are its inhibitors?
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- Thermogenin
- Inhibited by ATP, ADP, GTP, GDP |
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What are the two mechanisms for proton transport? Which one is more plausible?
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- Redox loop (redox centre accepts H+ and e- at same time)
- Proton pump (binds H+, reduction causes conformation change, release of H+, reoxidation) --> more plausible |
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Which subunits compose Fo ATP synthase?
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a1 b2 c12
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What is the function of the c subunits of Fo ATP synthase? What are they attached to?
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Act as a rotor attached to the gamma subunit.
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Is Fo ATP synthase located outside of the membrane or inside?
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Integral membrane protein
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Where is the proton channel of ATP synthase located?
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Where the a and c subunits meet
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What are the five subunits that compose F1 ATP synthase?
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alpha3, beta3, gamma, delta, epsilon
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Where is F1 ATP synthase located?
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In the matrix of the mitochondria, attached to the IMM
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What is the rotor of ATP synthase composed of?/
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gamma, epsilon, c12 subunits
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What composes the stator of ATP synthase?
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ab2 - alpha3, beta3, delta
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What is the purpose of the b2delta structure of the stator?
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Prevents the alpha3, beta3 subunits from moving
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What are the 3 states of the alpha3,beta3 subunit? aka mechanism of ATP synthesis
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O: low affinity, catalytically inactive
L: loose affinity, catalytically inactive T: high affinity, catalytically active |
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What does the L state subunit of ATP synthase bind?
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ADP + Pi
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Where does the energy for the change of state of the ATP synthase subunits come from?
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H+ gradient turns rotor, provides energy for the change of state.
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What does the T state become with energy?
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O state
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How was the rotation of ATP synthase demonstrated?
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Bound fluorescent actin filament to ATP synthase and watched it turn in presence of ATP.
BADASS! |
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How is phosphate transported inside the mitochondria?
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H+/Pi symport
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How is ADP moved into the mitochondria? ATP? How is this driven?
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They simultaneously moved by adenine nucleotide translocase.
Negative charge is transported out, so proton gradient drives the reaction. |
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Does gluconeogenesis use carbohydrate precursors?
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NO, only non-carbohydrate precursors.
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What is the starting material for gluconeogenesis?
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Oxaloacetate
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Is there a NET pathway to convert Acetyl-CoA to oxaloacetate? An indirect pathway?
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No net pathway.
Can go indirectly through CAC |
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True or False?
Gluconeogenesis is a reversal of glycolysis. |
False
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What are the four main enzymes involved in gluconeogenesis?
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Pyruvate carboxylase
PEPCK FBPase G6Pase |
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What are the substrate of pyruvate carboxylase? Does it use ATP?
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- Pyruvate and CO2
- Uses 1 ATP |
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What is released by PEPCK? Does it use ATP?
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- CO2 is released
- Uses GTP, not ATP |
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How is oxaloacetate transported out of the mitochondria?
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Malate/Aspartate Shuttle
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Which path is favoured for the export of oxaloacetate from the mitochondria under normal conditions? When doing exercise?
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- Malate --> produces 1 NADH
- Aspartate, since the gluconeogenic precursor is lactate, which can be oxidized back to pyruvate to form NADH |
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True or False?
G6Pase is found in almost every tissue. |
False, only in the liver
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What is the energetic cost of gluconeogenesis?
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2 ATP, 2 GTP
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Is the cost of doing gluconeogenesis worth it?
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Yes, it is the price to pay to maintain independent regulation.
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What are the inhibitors of FBPase?
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AMP, F26P
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What activates Pyruvate carboxylase?
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Acetyl-CoA
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What stimulates PEPCK? Inhibits?
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- Stimulated by glucagon, thyroid hormone, glucocorticoids
- Inhibited by insulin |
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What is the Cori cycle?
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Regulation between two tissues through bloodstream.
Lactate from muscle goes to liver, where it undergoes gluconeogenesis. Glucose is then sent back in blood. |
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Under long fasting conditions, what is Acetyl-CoA converted to?
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Ketone bodies
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What does the metabolism of alcohol produce in large quantities?
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NADH
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What effect does Alcohol have on the CAC? Gluconeogenesis?
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- Inhibition of CAC, due to high NADH level
- pyruvate shifts to lactate, oxaloacetate shifts to malate |
