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NADH and FADH come from the degredation of what substances
- Glucose
- Fatty acids
- Amino Acids
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Conversion of electron to proton motive force is carried out by what 3 electron pumps
- NADH-Q oxidoreductase
- Q-cytochrome c oxidoreductase
- Cytochrome c oxidase
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The electron driven pumps in oxidative phosphorylation contain what oxidation reduction centers
- Quinones
- Flavins
- Iron sulfur clusters
- hemes
- copper ions
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Oxygen is the ultimate acceptor of NADH and FADH2 forming what
H2O
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Electron carries can be either bound to proteins or
Diffuse freely in the membrane (most are soluble)
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Electron transport chains cannot
Exist free in solution, but must be bound to a membrane to exchange electrons
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The further electrons go down to succeeding reactions
The more exergonic they become
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The site of oxidative phosphorylation is where
In the inner membrane of the mitochondria
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NAD+ and NADH funnels 2e- into
Complex 1
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The NADH from glycolysis must do what to be incorporated into the electron transport chain
They must be transported from the outside of the mitochondrial membrane to the inside to reach Complex 1
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FMN/FMNH2 accepts and transfers electrons how
Singly or in pairs, and donates e- to CoQ
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FAD/FADH2 is a cofactor in what complex and funnels e- from where
Complex 2, funnels electrons from mitochondria succinate onto CoQ
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A pair of e- in FADH2 results in what in comparison to NADH
- FADH2 - 2 ATP
- NADH - 3 ATP
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Fe-S has what function in Oxidative Phosphorylation
Centers as a electron carrier, and is always complexed with proteins
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What are the diffusible e- carriers
- Coenzyme Q (isoprenoid)
- Cytochrome c (small protein)
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Coenzyme Q has what function
Can carry 1e- or 2e- into the respiratory chain Funnels e- into cytochromes towards oxygen
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What can coenzyme Q draw electrons from
- NADH
- Succinate
- FADH
- Other flavin enzymes
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What is the job of cytochrome c
Transfers e- between complexes 3 and 4 and cannot bind oxygen
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Which complexes are proton pumps
1, 3, 4
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What happens in complex 1
- It contains e- carriers FMN and FE-S
- Passes e- from NADH to CoQ
- Is a proton pump
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What is the job of complex 2
- Contains FAD and FE-S e- carriers
- Passes e- from succinate (TCA cycle) onto CoQ
- Not a proton pump
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What is the job of complex 3
- Contains Cyt b, FE-S, and cyt-c e- carriers
- Passes e- from CoQ to Cyt-c
- Is a proton pump
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What is the job of complex 4
- Contains electron carriers Cyt-a
- Passes e- from Cyt-c to Oxygen
- Is a proton pump
- Copper containing
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What is complex 5
The ATP synthase which uses the proton gradient
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How does a proton pump work
It is an integral protein in the mitochondrial inner membrane that physically moves protons from the matrix to the intermembrane creating an electrochemical potential which powers the ATP synthase
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The larger the reduction potential (E) the more
Negative Delta G and thus the more likely to transfer
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What is the order of the least strongest to the strongest oxidant on the transport chain
- NAD+
- FMN
- FAD
- CoQ
- Cyt b2 (Fe+3)
- O2
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What happens to the value of the reduction potential (E) as the electron transport chain moves along
It get larger, thus Delta G gets smaller
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The glycerol phosphate shuttle (FADH2-FAD) is particularly active where
In the brain and produces 2 ATP
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The malate aspartate shuttle is particularly active where
In the liver and heart and produces 3 ATP
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ATP is coupled to ADP entry into the mitochondria by
ATP-ADP translocase driven by membrane potential
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What are the substrates to oxidative phosphorylation, and what else to they
- ADP
- Pi
- O2
- NADH
- FADH2
- They are rate limiting as well
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What is the chemiosmotic theory
Electron transport creates an electron gradient outside the mitochondria (high e-) used for the ATP synthesis (proton motive force)
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What are the two units of the ATP synthase and their jobs
- F1 Contains the catalytic site for ATP synthesis (in matrix)
- F0 serves as a transmembrane channel (base) for H+ flow
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Rotenone
- Blocks electron flow from NADH to CoQ (not absorbed by humans well)
- Complex 1 inhibitor
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Amytal and other barbituates (Demerol) have what effect on Ox Phos
Complex 1 inhibitor
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Antimycin effects ox phos how
Blocks complex 3 (cytb -cytc1)
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Cyanide, azide, CO, and hydrogen sulfide have what effect on ox phos
Block complex 4
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Oligomyocin (antibiotic) has what effect on the ATP synthase
Inhibits F0
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2,4 dinitrophenol and Pentachlorophenol have what effect on ox phos
- They are uncoupling agents for e- carriers
- These do not interfere with electron transport and in fact stimulate it by providing an alternative pathway to disapate energy of electron transport
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How is energy conserved with an uncoupler like dinitrophenol
- Protons are driven out through the inner membrane like normal, however, they leak back in so rapidly that ATP synthesis does not occur.
- Instead, the energy conserved is dissipated as heat
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What is an endogenous uncoupler
Thermogenin (brown adipose tissue) keeps babies and hibernating animals warm by bypassing ATP synthesis and enhancing Complex's 1-4
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What are some endogenous sources for reactive oxygen species (ROS)
- Electron transport chains
- Mitochondria
- Phagocytes
- Flavins
- Oxidases
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Where is over 90% of the oxygen consumed in cells
Os Phos complex 4
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Oxygenases
Enzymes that use oxygen to form oxidized products
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Oxidase
An enzyme that promotes the transfer of a H from a substrate to an Oxygen making water or hydrogen peroxide
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What are some exogenous sources of ROS
- Ionizing radiation
- Light (visable/UV)
- Redox cycling xenobiotics
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What are some antioxidant enzymes
- Superoxide dismutase
- Catalase (Haem)
- Glutathione Peroxidase (Selenium)
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What are some low molecular weight antioxidants
- Vit C (ascorbic acid)
- Urate
- Albumin
- Vit E
- Beta carotene
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Tocopherols/Tocotrienols
Technical name of Vit E
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Peroxidase
Enzyme that catalyzes the oxidation of a substance by hydrogen peroxide
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Lebers hereditary optic neuropathy (LHON)
- Caused by a mutation in the mitochondrial DNA affecting the nervous system including the optic nerves
- Single base change for complex 1 making a defective e- transfer from NADH to ubiquinone
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