Cyanide blocks which specific component of the electron transport chain, and why is this disruption fatal to cells? Hint: Think about where oxygen is used in the mitochondria.
Added by Tracy A.
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Cyanide binds to cytochrome c oxidase, also known as Complex IV, in the ETC. Show more…
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Cyanide (CN⁻) poisoning stops cellular respiration by inhibiting the action of cytochrome c oxidase enzymes in the mitochondria. Specifically, cyanide blocks complex IV of the electron transport chain. What does this suggest about oxygen's role as an electron acceptor?
Sri K.
1) Cyanide is poisonous because it blocks complex iV in the electron transport chain. What step in electron transport would be most immediately affected by cyanide poisoning? A) the production of NADH. B) the reduction of oxygen. C) the transfer of electrons by the mobile electron carrier, CoQ D) the operation of citric acid cycle 2) One might think that blocking the electron transport chain and cellular respiration would not kill a person because glycolysis, which is not affected by cyanide, would continue to produce energy and keep a person alive. But that's not the case. Why? A) Glycolysis utilizes oxygen which would be in short supply. B) Glycolysis utilizes glucose which would be depleted by the action of cyanide. C) Glycolysis makes insufficient ATP to maintain our bodily functions. D) Glycolysis is a mitochondrial process and mitochondrial functions would be blocked cyanide.
Pahal S.
Given what you now know about the action of cyanide on cellular respiration, explain why the patients died of lack of oxygen while their blood oxygen levels were normal? Cyanide attaches itself to the cytochrome oxidase, which is part of complex IV of the electron transport chain (ETC), and changes its configuration. This alteration makes it impossible for the complex to transfer H+ ions to the intermembrane space and synthesize them into water with oxygen. By blocking this crucial step, cyanide effectively disrupts the entire electron transport chain. ATP is no longer produced under aerobic conditions, and the cells quickly die from a condition called histotoxic anoxia (cellularly toxic lack of oxygen). So, even though oxygen is available to the cell, it is not being utilized in the ETC due to cyanide's effect. Therefore, in this case, the death is not due to a lack of oxygen.
Lochan U.
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