Oxidative Phosphorylation Flashcards
What is oxidative phosphorylation?
the oxidation of NADH by O2
- 3 major protein complexes
- 2 mobile carriers
- cytochromes and iron-sulphur proteins
Where is the location of oxidative phosphorylation?
carried out by membrane proteins in the inner mitochondrial membrane
What are the three protein complexes involved in the oxidation of NADH?
I = NAHD dehydrogenase III = Cyt b/c1 complex IV = Cytochrome Oxidase
What are the 2 mobile carriers involved in the oxidation of NADH?
UQ = Ubiquinone Cytc = Cytochrome C
What are the half equations for the oxidation of NADH?
NAD+ + H+ + 2e- NADH
0.5O2 + 2H+ + 2e- H2O
What does Ochoa’s experiment show?
- ADP stimulates a burst of respiration in isolated mitochondria
- Respiration is obligatorily coupled to phosphorylation of ADP
What is the 1st postulate of the chemiosmotic hypothesis?
H+ Pump
Evidence: H+ ejection from the mitochondrion can be measured directly with sensitive pH electrodes
What is the 2nd postulate of the chemiosmotic hypothesis?
Membrane permeability
- inner membrane is impermeable to H+
- some reagents can inhibit ATP synthesis but not electron transport by making the membrane leaky to protons
What is the role of uncouplers
short-circuit the flow of protons
What is the 3rd postulate of the chemiosmotic hypothesis?
ATP synthase
What is the 4th postulate of the chemiosmotic hypothesis?
Inner membrane exchange carriers
- anion entry is coupled to proton entry
- cation exit is coupled to proton entry
- transmembrane exchange
- provides a thermodynamically favourable solution
What is a protonmotive force?
links energy generating and consuming systems in many cellular systems
energy is generated by the transfer of protons or electrons across an energy transducing membrane
What does the chemiosmotic mechanism predict
predicts that any H+ pump should drive ATP synthesis
