Final answer:
Cyanide poisoning inhibits cytochrome c oxidase in the ETC, leading to the cessation of electron transport and ATP synthesis, with a resultant increase in pH of the intermembrane space due to decreased proton concentration.
Step-by-step explanation:
Cyanide is a toxic chemical that has devastating effects on cellular respiration, particularly by inhibiting a crucial enzyme in the electron transport chain (ETC). When cyanide enters the body, it binds to cytochrome c oxidase, also known as complex IV of the ETC, which competes with oxygen. This enzyme is responsible for the final step in the chain, where electrons are transferred to molecular oxygen, creating water.
As cyanide inhibits cytochrome c oxidase, the ETC grinds to a halt because electrons can no longer flow through it. This blockage means that the proton gradient across the inner mitochondrial membrane, which drives ATP synthesis, cannot be maintained. Hence, ATP synthesis is severely impaired. As the protons cannot be pumped into the intermembrane space, we would expect the pH of the intermembrane space to increase due to a decrease in proton concentration.
Cyanide poisoning represents a form of histotoxic hypoxia where cells cannot utilize oxygen, leading to a shift towards anaerobic respiration, increased lactic acid production, and consequently, metabolic acidosis. This shift away from aerobic respiration and the resulting loss of ATP production can be quickly fatal, as ATP is essential for almost all cellular functions.