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70 Cards in this Set
- Front
- Back
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Where does oxidative phosphorylation take place? |
In the mitocodria |
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Where do the electrons for oxidative phosphorylation come from?? |
NADH and FADH oxidation in the TCA cycle. |
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What happens to the energy released in each stage of oxidative phosphorylation? |
It is conserved in the form of a proton gradient |
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What is ^Eo’ equal to? |
Eo’ (e- acceptor) - Eo' (e- donor) |
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What is ^G0' equal to? |
-nF^Eo' |
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The relationship between ^Eo' and ^Go' is? |
When ^Eo' is positive ^Go' is negative |
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As you go down the electron transport chain what happens to the ^Eo' values? |
They go from very negative to very positve |
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What do reduced flavins do? |
Act as hydrogen carriers (both protons and electrons) |
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Where are FeS clusters bound? |
To the cysteine residues of polypeptides |
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What do FeS clusters do? |
The iron atom can be oxidised and reduced so can carry electrons |
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What can quinones do? |
Act as hydrogen carriers (both protons and electrons) |
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Name a featuure of quinone |
It is lipophilic so can act as a carrrier between proteins and complexes |
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What is complex 1? |
NADH-Q oxidoreductase |
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Whats the overall reaction of complex 1? |
NADH + Q + 5H+ (matrix) ---- NAD+ + QH2 + 4H+ (cytosol) |
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What is the electron path for complex 1? |
NADH + H+--FMN--4Fe/4S--4Fe/4S--4Fe/4S--Q((H2)mat c1)--Q((H2)Inmem c1)--(Q(H2) out of complex)) |
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How many protons are pumped across the inner membrane with complex 1 per 2e- from NADH to ubiquinone? |
4H+ |
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What is complex 2? |
Succinate dehydrogenase |
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What is the reaction for complex 2? |
Succinate + FAD+ -- fumarate + FADH2 |
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What is the electron carrier for complex 2 and how does it do this? |
FAD FAD is reduced and passes its electrons to ubiquinone via FeS |
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How many protons are pumped by complex 2? |
0H+ |
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What is complex 3? |
Q-cytochrome c oxidoreductase |
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How many heme groups are in complex 3? |
3. c1 ,bL and bH |
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How is the Rieske iron-sulpur centre stabalised in complex 3? |
Co-ordination by His. The reduced form is stabalised so raising the reduction potential. |
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How do different cytochromes differ? |
The nature of the side chains on the porphyrin ring The linkage to the protein (cov or non-cov a/b) The protein environment |
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What is a common type of linkage between the protein and cytochrome? |
Thioether linkages |
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What is the overall reaction of complex 3? |
QH2 + 2cytcox + 2H+mat ----- Q + 2cytcred + 4H+ cytosol |
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What is electron transfer with complex 3 known as? |
The proton motive Q-cycle |
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Electron transfer of complex 3? |
2 electrons from QH2 at Qo sit take different routes. 1 transferred RIeske FeS centre--cyt c1--- Cty c. 2 cyt bL--- cyt bH--- oxidises Q molecule at Qi site. 2 protons QH2 released into cytosol. Q at Qo replaced cycle repeated. Semiquone intermediate at Qi reduced QH2 by second e- transfer from Qo + 2H+ from matrix. |
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What is complex 4 known as? |
Cytochrome c oxidase |
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How many heme groups in complex 4? |
2. a and a3 |
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What is the reaction of complex 4? |
4 cyt c red + 4H+mat + O2 --- 4cyt c ox + 2H2O |
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Where do the protons come from for complex 4's reaction and how many are needed? |
From the matrix. 4 |
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How many mechanisms are there for complex 4? |
2 |
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First mechanism for complex 4? |
Electron transferred to CuB Electron transferred to Fe in heme a3 Both CuB and Fe are in heme a3 reduced states O2 binds to Fe |
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What type of bridge forms between Fe2+ and O2? |
Peroxide |
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Mechanism 2 of complex 4? |
Peroxide bridge forms The O-O bond is cleaved (due to e- from the cyt c and H+ from the matrix) The ferryl group is reduced to -OH (another e- from cty c and another H+ from the matrix). Water is released, (two more H+ from the matrix) |
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What is the proton transfer of complex 4? |
4 chemical protons 4 pumped protons per 4e- transferred and O2 reduced |
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In ATP synthase which sections are located in the membrane and which are in the matrix? |
Fo is in the membrane F1 is in the matrix |
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What is complex 5 also known as? |
ATP synthase |
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How many subunits is F1 compromised of? |
6. 3 alpha, 3 beta |
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Which F1 subunits are regulatory and which are catalytic? |
Beta are catalytic and alpha are regulatory |
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What connects F1 to Fo |
Gamma subunit |
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What does Fo compromise of? |
A ring of hydrophobic proteins which act as a H+ channel |
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Basic description, how does ATP synthase work? |
The protons flow through the F0 channel, causing it to rotate. This turns the gamma subunit which drives conformational changes in the alpha and beta subunits. |
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How many c subunits are in the protein channel? How many H+'s can each c subunit carry |
8, each can carry 1 H+ per rotation |
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How many ATP are made in one complete rotation? |
3 |
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What are the three binding states of ATP in ATP synthase? |
Open, loose and tight. |
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What does the P:O ratio describe? |
How many molecules of ATP can be made per oxygen atom reduced to water. |
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What are the principal light harvesting molecules? |
(bacterio)chlorophylls |
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What is Rhodopseudomonas viridis? |
Photosynthetic bacterium |
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What happens with charge separation? |
Exitation of electrons causes an electron being transferred to adjacent acceptor leaving an oxidised donor and a reduced acceptor |
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What are the areas that harness charge separations called? |
Photosynthetic reaction centres |
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How does light turn into chemical energy? |
Light excites an electron in p960. Charge separation occurs, p960 is oxidised and BPh is reduced. P960+ is rexidised by a reduced heme. BPh- reduces Qa. Qa reduces Qb with a H+ from the matrix. Pathway repeats producing a quinone pool of QH2. |
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What happens to the QH2 produced by the bacterial reaction centre? |
It is reoxidised by complex 3 (Q-cytochrome c oxidoreductase). The cytochrome subunit is re-reduced by cytochrome c2. |
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What is generated in the reaction centre/complex 3 interaction? |
A proton gradient, if anaerobic in the presence of light. The process is cyclic. |
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What is the net reaction of photosynthesis in a chloroplast? |
2H2O + 2NADP+ --- O2 + 2NADPH + 2H+ |
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What is PSII? |
Photosystem II. |
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What does PSII consist of? Where is it loccateed |
D2 and D1 core proteins, special pair in D2 protein. An oxygen evolving complex with a Mn centre. Chlorophylls bound to additional protein subunits. Located in membrane between stroma and thylakoid lumen. |
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Describe electron transfer through PSII |
Light excites electrons in P680. Charge spearation occurs, one elctron goes to Mn4 centre, 2H2O --- O2, the electrons come from the water. One electron reduces pheophytin. This in turn reduces plastoquinone at the Qa site. This reduces exchangeable plastoquinone at site Qb. |
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What is PSII, D1 and D2 functionally equivalent to in bacteriophotosynthesis? |
The bacterial reaction centre, L and M |
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What does PSII use as an electron donor? |
Water |
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What oxidises reduced plastoquinone? |
Cytochrome b6f complex |
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What is cty b6f homologous to in mitochondria? |
Cyt bc1. They both contain a Reiske 2Fe2S cluster |
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What metal ion does plastocyanin carry? What is it? |
Copper. Its an electron carrier between the bf complex and PSI, analogous to cyt c |
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How many protons does cyt bf transfer? |
4 |
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How many FeS clusters are there in PSI? |
4 |
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What wavelengths do cartenoids absorb? |
400-500nm |
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Where are the various photosynthetic complexes found in the thylakoid membrane? |
PSI and ATP synthase in the unstacked region. PSII in the stacked region. b6f in both |
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What are the big five of the plat hormone business? |
Auxin, cytokinins, ethylene, gibberellines and ABA |
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What are jasmonates? |
Plant, fatty acid derived signals analogous to prostagladins |
