Cyanide (C≡N−) blocks complex IV of the electron transport chain. Suggest a hypothesis for what happens to the ETC when complex IV stops working. Your hypothesis should explain why cyanide poisoning in humans is fatal.

Verified step by step guidance

1. Understand the role of complex IV in the electron transport chain (ETC). Complex IV, also known as cytochrome c oxidase, is responsible for the final step of electron transfer to oxygen, forming water.
2. Recognize that when complex IV is blocked by cyanide, electrons cannot be transferred to oxygen. This halts the entire electron transport chain because the flow of electrons is interrupted.
3. Consider the impact on ATP production. The ETC is crucial for creating a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis through oxidative phosphorylation. If the ETC stops, ATP production is severely reduced.
4. Hypothesize that without ATP, cells cannot perform essential functions. ATP is the primary energy currency of the cell, and its absence leads to cellular energy failure.
5. Conclude that cyanide poisoning is fatal because it prevents ATP production, leading to the failure of critical cellular processes and ultimately causing cell death.

Key Concepts

Electron Transport Chain (ETC)

The Electron Transport Chain is a series of protein complexes located in the inner mitochondrial membrane that facilitate the transfer of electrons from electron donors to electron acceptors. This process is crucial for ATP production through oxidative phosphorylation, where energy from electrons is used to pump protons across the membrane, creating a proton gradient that drives ATP synthesis.

Complex IV (Cytochrome c oxidase)

Complex IV, also known as cytochrome c oxidase, is the final enzyme in the electron transport chain. It catalyzes the transfer of electrons from cytochrome c to molecular oxygen, reducing it to water. This step is essential for maintaining the flow of electrons through the ETC and for the overall production of ATP, as it helps to sustain the proton gradient necessary for ATP synthesis.

Cyanide Poisoning

Cyanide poisoning occurs when cyanide ions bind to Complex IV, inhibiting its function and preventing the reduction of oxygen. This blockage halts the electron transport chain, leading to a rapid decrease in ATP production and a buildup of toxic byproducts. The lack of ATP disrupts cellular metabolism, particularly in high-energy-demand organs like the heart and brain, ultimately resulting in cell death and can be fatal if not treated promptly.