Final answer:
Antimycin-A is the drug that inhibits Complex III of the electron transport chain, which affects the ATP production by disrupting the proton gradient required for oxidative phosphorylation.
Step-by-step explanation:
The drug that inhibits Complex III of the electron transport chain (ETC) is antimycin-A. Complex III, also known as cytochrome c reductase or cytochrome bc₁ complex, plays a crucial role in the ETC. It contains protein subunits, an iron-sulfur cluster, and cytochromes which help in transferring electrons. Antimycin-A acts by stopping the flow of electrons through this complex, specifically from cytochrome b to cytochrome c1, which in turn hinders the electron transport chain and the process of oxidative phosphorylation. This inhibition disrupts the production of ATP as the hydrogen ion gradient across the membrane is not effectively established.
In the context of oxidative phosphorylation, uncouplers are substances that disrupt the link between the electron transport chain and ATP synthesis without necessarily affecting the flow of electrons. An example of this would be the introduction of a chemical that makes the mitochondrial membrane permeable to protons, thereby eliminating the proton gradient used to power ATP synthase.