Question

A) How does an uncoupler disrupt oxidative respiration?

1. Preventing reduction of O2

2. Stopping the flow of electrons through the ETS

3. inhibit oxidation w/o affecting phosphorylation

4. making the membrane permeable to protons

B) Which of the following molecules does NOT participate in the reaction catalyzed by the pyruvate dehydrogenase complex?

1. lipoic acid

2. CoA-SH

3. dihydrolipoyl dehydrogenase

4. phosphoenolpyruvate

Answer 1

1.  making the membrane permeable to protons

Uncouplers increase the permeability of the inner mitochondrial membrane to protons. Example 2,4-dinitrophenol, is a lipophilic proton carrier that can readily diffuses through the mitochondrial membrane. The electron transport can be carried out without having to establish a proton gradient as the permeability is increased.

2. dihydrolipoyl dehydrogenase does not participate in the  in the reaction catalyzed by the pyruvate dehydrogenase complex