Electron transfer and oxidative phosphorylation Flashcards
1
Q
what happens in oxidative phosphorylation
A
the energy released from the oxidation os NADH and FADH2 is used to synthesize ATP
2
Q
why use the Electron transport chain
A
- reducing equivalents from reduced cofactors are passed to oxygen indirectly
- reoxidation of NADH and FADH2 is broken up into processes with smaller free energy changes
3
Q
what done the ETC comprise of
A
- set of electron carriers arranged in order of increasing reduction potential
- oxygen is the terminal e- acceptor
- 4 unique enzymes (complexes) that catalyze transfer of e- form one carrier to another
4
Q
complexes (enzymes)
A
I: NADH hydrogenase
II: succinate dehydrogenase
III: cytochrome c reductase
IV: cytochrome oxidase
5
Q
coenzyme Q (ubiquinone)
A
- can accept one e- (semiquinone .QH) or 2e- (ubiquinol QH2)
- can freely move in the membrane, carrying e- from one ETC complex to another
6
Q
cytochrome c
A
- in the mitochondrial inter membrane space and shuttles e- from complex III to IV
7
Q
ETC process
A
- complex I and II transfer e- to Q, reducing it to QH2
- QH2 passes electrons to cytochrome c through complex III
- complex IV transfers e- from reduced cytochrome c to O2
- electron flow through I, III and IV is accompanied by proton flow from the matrix to the IMS
8
Q
CoQ collects reducing equivalents from…
A
- complex I (NADH)
- complex II (FADH2)
- complex III (FADH2)- through a series of electron carriers
- glycerol-3-phosphate dehydrogenase shuttle (FADH2)
9
Q
proton gradient
A
- conserves the energy available through the oxidation NADH and FADH2
- for each pair of e- transferred from NADH to O2, 4 H+ from complex I, 4H+ from complex III and 2H+ by complex IV are pumped
- electrons from FADH2 bypass complex I and 6 protons are pumped per FADH2
- energy stored in the proton gradient is the proton motive force
10
Q
what happens to the energy of the proton gradient in the presence of an uncoupler
A
- the energy is not conserved by ATP formation so it dissipates as heat