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Below is a generic drawing of a mitochondrial (mt) electron transport chain with the 4 electron transfer complexes (I-IV), associated proton pumping, and the ATP synthase shown relative to the inner membrane, as labeled.

Use your understanding of the Chemiosomotic theory and this drawing as a reference to determine which of the following statements accurately describes the coupling of electron transport with ATP synthesis as studied in isolated animal mitochondria.

M. Rumpho-Kennedy. Created for Copyright 2016. All rights reserved.


In the presence of the uncoupler dinotrophenol (DNP; see structure below), electron transfer and oxygen consumption will continue, but ATP synthesis will decrease. DNP is a lipophilic proton transporting ionophore that dissipates the proton gradient.

MantOs. DNP. Wikimedia Commons, 18 Jan. 2007. Web. 5 Feb. 2016.


In the presence of oligomycin, which physically blocks the ATP synthase proton channel, electron transfer and oxygen consumption will increase, but ATP synthesis will decrease.


In the presence of cyanide, an inhibitor of cytochrome oxidase, electron transfer from NADH or succinate will decrease. However, oxygen consumption will increase and heat will be generated.


In the presence of an inhibitor of electron flow from NADH to complex III, electron transfer and ATP synthesis will stop.

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