Question

2,4-dinitrophenol (DNP) is a weak acid that can diffuse across lipid membranes. When added to eukaryotic cells, DNP can enter the mitochondria and move protons between the intermembrane space and the mitochondrial matrix by binding protons on one side, diffusing across the inner mitochondrial matrix and releasing protons on the other side, i.e. move protons down their concentration gradient across the inner mitochondrial membrane.
a. How will DNP affect the proton gradient generated by ETC?
b. Will the addition of DNP inhibit the ETC, ATP synthase or both? Briefly explain your answer.

Answer 1

Answer:

a. In the presence of 2,4 dinitrophenol, which is soluble through the lipid membranes, the H+ gets an another route to pass through the membrane. It hampers the proton gradient potential without any generation of ATP. The gradient that was being utilized for the generation of energy is now just lost in the form of heat.  

b. With the reduction in the generation of energy, the cells get devoid of ATP, and drive the electron transport chain intensely so that the collapsing proton gradient gets re-established. However, it prevents the ATP synthase by providing a different path to the proton ions and thus diminishing the H+ concentration gradient.