How is Respiration affected in the mitochondria.

Question

The electrochemical energy inherent in the difference in proton concentration and the separation of charge across the inner mitochondrial membrane drive the synthesis of ATP as protons flow passively back into the matrix through the proton pore in ATP synthase.

ADP+P_i+nH_p⁺---> ATP + H₂O + nH_N^+.

The mitochondrial membrane is not completely permeable to molecules, which allows for the processes to happen.

Now lets change the mitochondrial membrane to being completely permeable to molecules. How does this affect respiration?

I assume the ATPase can not longer function as O₂ does not proceed. Which would mean respiration would stop????

Answer 1

You're mostly correct! We have two processes occurring in the mitochondrial matrix membrane. The first is the flow of electrons from NADH and FADH2 through complexes I-IV and then finally onto O2, which is reduced to H2O. The second processes is using the energy gradient and flow of protons pumped by complexes I, III, and IV back into the membrane in order to synthesize ATP. Normally, these protons flow through ATP synthase, giving it the energy to make ATP. However, if protons can flow directly through the membrane, they no longer flow through the synthase, thus "uncoupling" the pumping of protons from ATP synthesis. This means that we no longer make ATP, and all that energy is released as heat within the cell. This process can occur naturally in animals that spend a lot of time outside in cold weather, as a form of creating heat from macro-molecules instead of ATP.

However, O2 can still proceed. While ATP cannot be made, electrons can still flow freely through the ETC and onto O2, reducing it to H2O.

So, although ATP synthesis will stop, O2 can still be used.