Final answer:
Cyanide inhibits cytochrome c oxidase, preventing electron transfer to oxygen, increasing the intermembrane space pH, and halting ATP synthesis.
Step-by-step explanation:
Cyanide is a poison that blocks the transfer of electrons from cytochrome c oxidase to oxygen, thus inhibiting the electron transport chain and the production of most of the ATP through oxidative phosphorylation. This disruption causes a decrease in the pH of the intermembrane space. In addition, cyanide inhibits the synthesis of ATP, as ATP synthesis is dependent on the proton gradient created by the ETC.
Cyanide inhibits the enzyme cytochrome c oxidase, which is an essential component of the electron transport chain (ETC), located in the inner mitochondrial membrane. The binding of cyanide to this enzyme prevents the transfer of electrons to oxygen, the final electron acceptor. Without this electron transfer, the proton gradient across the mitochondrial membrane cannot be maintained. As a result, the pH of the intermembrane space would increase due to the lack of protons being pumped into it. This disruption halts the ability of ATP synthase to generate ATP, leading to a drastic reduction in cellular ATP synthesis. Cyanide poisoning is a lethal condition because ATP is critical for many cellular processes and is the primary energy currency of the cell. The inhibition of ATP production rapidly leads to cell dysfunction and death. Oxygen is essential for the generation of ATP, and its utilization is blocked in the presence of cyanide, causing histotoxic hypoxia and a collapse of aerobic metabolism.