Multiple Choice
In oxidative phosphorylation (using the modern P/O ratio), approximately how many ATP molecules are generated per mitochondrial NADH oxidized by the electron transport chain?
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Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation
Oxidative Phosphorylation 1
Multiple Choice
In oxidative phosphorylation, cyanide inhibits which protein complex of the electron transport chain, preventing the reduction of oxygen to water?
A
Complex I (NADH dehydrogenase)
B
ATP synthase (Complex V)
C
Complex IV (cytochrome c oxidase)
D
Complex II (succinate dehydrogenase)
Verified step by step guidance1
Understand that oxidative phosphorylation involves a series of protein complexes (Complexes I-IV) in the electron transport chain (ETC) that transfer electrons and ultimately reduce oxygen to water.
Recall that Complex IV, also known as cytochrome c oxidase, is the final protein complex in the ETC responsible for transferring electrons to oxygen, the terminal electron acceptor, reducing it to water.
Recognize that cyanide acts as an inhibitor by binding to Complex IV, specifically blocking the electron transfer to oxygen, which halts the entire electron transport chain.
Note that inhibition of Complex IV prevents the formation of the proton gradient needed for ATP synthesis, effectively stopping oxidative phosphorylation.
Conclude that cyanide's inhibitory effect is specific to Complex IV (cytochrome c oxidase), not Complex I, II, or ATP synthase (Complex V).
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