Lecture 30 - Oxidative Phosphorylation: ATP synthase Flashcards
What is the proton-motive force (pmf)?
A force created across the inner mitochondrial membrane from the proton gradient
What 2 energetic gradients create the pmf?
- A chemical gradient or pH gradient due to different H+
concentrations on either side of the membrane - An electrical gradient due to the charge difference across
the membrane (positive in the intermembrane space,
negative in the matrix)
What type of gradient is the pmf?
Electrochemical
What happens when mitochondria are isolated from cells and have the outer membrane removed?
- Electron transport chain still works
- But ATP is not made
What is Bacteriorhodopsin?
A light inducible proton pump (pumps protons to make a proton gradient in light)
What happens to the ATP synthase in an artificial liposome containing a bacteriorhodopsin?
Makes ATP when light switched on
Is there an electron transport chain in an bacteriorhodopsin containing artificial liposome?
NO
What is 2,4-Dinitrophenol (DNP)?
An uncoupler
How does DNP uncouple?
Shuttles H+ from intermembrane space to the matrix dissipating the proton gradient
WHat happens in the presence of DNP?
ETC functions, but no ATP is made (no H+ grad)
What does DNP prove?
The pmf is necessary for ATP synthesis
What does removing the outer mitochondrial membrane prove?
This proves than ATP is not synthesised in the ETC, and outer membrane is required for formation of pmf
What does bacteriorhodposin containing artificial liposomes prove?
The proton gradient is sufficient for ATP synthesis without the ETC
What happens if you take DNP?
- Fuel molecules still undergo CAC, B-Oxidation, Pyruvate dehydrogenase
- Coenzymes are reduced
- ETC functions
- No ATP is made
What happens to the energy stored in the pmf in presence of DNP?
Released in the form of heat rather than ATP
