Which of the following statement is true regarding “Cyanide”?

A. Only minimally inhibits the ETC because cytochrome oxidase is the terminal component of the chain

B. Inhibits mitochondrial respiration but energy production is unaffected

C. Also binds the copper of cytochrome oxidase

D. Bind to Fe+++ of cytochrome a3

Correct Answer: Bind to Fe+++ of cytochrome a3

Description: Cyanide reversibly binds to the ferric ion in cytochrome oxidase a3 within the mitochondria, effectively halting cellular respiration by blocking the reduction of oxygen to water. That is why methemoglobin is an effective antidote since it also has Fe+++.Respiration and energy production is the coupled process, so inhibition of one inhibits the other as well.Cu is an impoant pa of cytochrome oxidase, but cyanide does not bind it.

Category: Microbiology

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