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Animation: Electron Transport Chain: Factors Affecting ATP Yield

by Pearson
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Let's look at the effects of certain factors on ATP yield, beginning with lack of oxygen. When the final electron acceptor is not available to an electron transport chain, the chain shuts down, and is unable to continue to pump protons across the membrane. When the proton gradient is removed, ATP synthase can no longer produce ATP. Cyanide poisoning acts in a manner similar to oxygen deprivation. Cyanide blocks cytochrome a3, preventing that complex from reducing oxygen. With cytochrome a3 stuck in the reduced state, the other components of the chain are unable to change to the oxidized state. The proton gradient breaks down, The proton gradient breaks down, and ATP synthesis is halted. The proton gradient breaks down, The proton gradient breaks down, and ATP synthesis is halted. Some proteins use the proton gradient for some task other than producing ATP. These proteins are called “uncoupling proteins,” because they uncouple or disconnect the electron transport chain from ATP synthesis. For example, thermogenin is a protein found in certain mammalian fat cells. Thermogenin uses much of the energy of the proton gradient to produce heat to keep the mammal warm, thus reducing the yield of ATP.
Let's look at the effects of certain factors on ATP yield, beginning with lack of oxygen. When the final electron acceptor is not available to an electron transport chain, the chain shuts down, and is unable to continue to pump protons across the membrane. When the proton gradient is removed, ATP synthase can no longer produce ATP. Cyanide poisoning acts in a manner similar to oxygen deprivation. Cyanide blocks cytochrome a3, preventing that complex from reducing oxygen. With cytochrome a3 stuck in the reduced state, the other components of the chain are unable to change to the oxidized state. The proton gradient breaks down, The proton gradient breaks down, and ATP synthesis is halted. The proton gradient breaks down, The proton gradient breaks down, and ATP synthesis is halted. Some proteins use the proton gradient for some task other than producing ATP. These proteins are called “uncoupling proteins,” because they uncouple or disconnect the electron transport chain from ATP synthesis. For example, thermogenin is a protein found in certain mammalian fat cells. Thermogenin uses much of the energy of the proton gradient to produce heat to keep the mammal warm, thus reducing the yield of ATP.