Uncoupling the Mitochondrial Proton Gradient
A student isolates intact mitochondria and provides them with oxygen and an oxidizable substrate. The mitochondria produce ATP at a steady baseline rate. The student then adds a chemical (an uncoupler) that makes the inner mitochondrial membrane freely permeable to H⁺ ions.
(a)Describe what happens to the proton (H⁺) gradient across the inner mitochondrial membrane after the uncoupler is added. [1 pt]
(b)Predict the effect on the rate of ATP synthesis by ATP synthase, and justify your prediction. [2 pts]
(c)Predict how the rate of oxygen consumption will change, and explain the mechanism. [2 pts]
(d)Identify the form of energy that the released free energy from electron transport is now converted into instead of ATP, and explain why this could be physiologically useful in some organisms (such as in brown fat tissue of mammals). [2 pts]