Name: electron transport chain powers atp output
Uploaded: 2025-06-12T09:34:38.000Z
Duration: 1 min 22 s
Channel: JoVE

Au cours de la chaîne de transport d’électrons, les électrons de haute énergie du NADH et du FADH₂ traversent les complexes protéiques qui entraînent le pompage des protons à travers la membrane. Les électrons du NADH pénètrent dans le complexe I et se déplacent à travers les complexes, pompant environ dix protons à travers les complexes I, III et IV. Les électrons de FADH₂ entrent dans le complexe II, qui ne pompe pas de protons. En conséquence, FADH2 contribue à pomper seulement six protons à travers la membrane. Le mouvement des protons crée à la fois un gradient de concentration et un gradient électrique, générant collectivement la force motrice du proton. Les protons refluent à travers la membrane par l’intermédiaire de l’ATP synthase, un complexe enzymatique lié à la membrane qui utilise la force motrice des protons pour phosphoryler l’ADP en ATP - un processus appelé chimioosmose. L’ATP synthase utilise environ quatre protons pour synthétiser une molécule d’ATP. En conséquence, environ 2,5 molécules d’ATP sont générées par NADH, et environ 1,5 molécules d’ATP sont produites par FADH₂.

chimiosmose

Chemiosmosis and ATP Synthesis

La cha&#238;ne de transport des &#233;lectrons constitue un &#233;l&#233;ment cl&#233; de la respiration cellulaire, se d&#233;roulant dans la membrane mitochondriale interne. Elle facilite le transfert d&#8217;&#233;lectrons &#224; haute &#233;nergie depuis les cofacteurs r&#233;duits NADH et FADH_2 vers l&#8217;oxyg&#232;ne mol&#233;culaire, l&#8217;accepteur final d&#8217;&#233;lectrons. Ce transfert d&#8217;&#233;lectrons &#224; travers une s&#233;rie de complexes prot&#233;iques est &#233;troitement coupl&#233; &#224; la translocation de protons &#224; travers la membrane, g&#233;n&#233;rant un gradient de protons essentiel &#224; la synth&#232;se d&#8217;ATP.
Flux d&#8217;&#233;lectrons et pompage des protons
Les &#233;lectrons issus du NADH entrent dans la cha&#238;ne de transport au niveau du Complexe I (NADH:ubiquinone oxydor&#233;ductase). Chez les procaryotes, &#224; mesure que les &#233;lectrons traversent le Complexe I, ils induisent le pompage de protons depuis le cytoplasme vers l&#8217;espace extracellulaire. Les &#233;lectrons sont ensuite transf&#233;r&#233;s &#224; l&#8217;ubiquinone (coenzyme Q), qui les transporte jusqu&#8217;au Complexe III (complexe cytochrome bc1). Le Complexe III assure le transfert ult&#233;rieur des &#233;lectrons vers le cytochrome c tout en pompant davantage de protons. Enfin, les &#233;lectrons atteignent le Complexe IV (cytochrome c oxydase), o&#249; ils r&#233;duisent l&#8217;oxyg&#232;ne mol&#233;culaire en eau. Ce complexe participe &#233;galement &#224; la translocation de protons. Globalement, le passage des &#233;lectrons issus du NADH permet le pompage d&#8217;environ dix protons &#224; travers la membrane.
En revanche, les &#233;lectrons provenant du FADH_2 entrent dans la cha&#238;ne au niveau du Complexe II (succinate d&#233;shydrog&#233;nase), contournant le Complexe I. Le Complexe II ne poss&#232;de pas de capacit&#233; de pompage de protons. Les &#233;lectrons issus du FADH_2 sont transf&#233;r&#233;s &#224; l&#8217;ubiquinone et suivent un chemin similaire via les Complexes III et IV. Le FADH_2 contribue ainsi &#224; la translocation de seulement six protons &#224; travers la membrane.
Force proton-motrice et synth&#232;se d&#8217;ATP
Le pompage diff&#233;rentiel des protons engendre &#224; la fois un gradient chimique (de concentration) et un gradient &#233;lectrique (de potentiel) &#224; travers la membrane mitochondriale interne, ensemble d&#233;sign&#233;s sous le nom de force proton-motrice. Ce gradient &#233;lectrochimique entra&#238;ne le retour des protons dans la matrice mitochondriale via l&#8217;ATP synthase, un complexe enzymatique int&#233;gr&#233; &#224; la membrane. Le processus consistant &#224; exploiter la force proton-motrice pour phosphoryler l&#8217;ADP en ATP est appel&#233; chimiosmose.
L&#8217;ATP synthase n&#233;cessite environ quatre protons pour synth&#233;tiser une mol&#233;cule d&#8217;ATP. En raison des diff&#233;rences d&#8217;efficacit&#233; de translocation des protons, l&#8217;oxydation d&#8217;une mol&#233;cule de NADH g&#233;n&#232;re environ 2,5 mol&#233;cules d&#8217;ATP, tandis qu&#8217;une mol&#233;cule de FADH_2 en produit approximativement 1,5. Cette efficacit&#233; illustre le r&#244;le fondamental de la cha&#238;ne de transport des &#233;lectrons et de la force proton-motrice dans le m&#233;tabolisme &#233;nerg&#233;tique cellulaire.

Chimiosmose

La cha&#238;ne de transport des &#233;lectrons constitue un &#233;l&#233;ment cl&#233; de la respiration cellulaire, se d&#233;roulant dans la membrane ...

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Microbiology

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Microbial Metabolism

Métabolisme microbien

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

electron transport chain powers atp output

The electron transport chain powers ATP production during cellular respiration. It sits in the inner mitochondrial membrane and moves high-energy electrons from NADH and FADH2 to molecular oxygen, the final electron acceptor. As electrons move through the chain, protons are pushed across the membrane to build the gradient needed for ATP synthesis.

Electrons from NADH enter the chain at Complex I, also called NADH: ubiquinone oxidoreductase. In prokaryotes, this step helps pump protons from the cytoplasm into the extracellular space. The electrons then move to ubiquinone, or coenzyme Q, which carries them to Complex III, where more protons are pumped and electrons are passed to cytochrome c.

From Complex III, the electrons reach Complex IV, or cytochrome c oxidase. Here, molecular oxygen is reduced to water. Complex IV also helps move protons across the membrane. Overall, electrons that start with NADH lead to the pumping of about ten protons.

FADH2 follows a different route. Its electrons enter at Complex II, also called succinate dehydrogenase, which bypasses Complex I and does not pump protons. The electrons then move to ubiquinone and continue through Complex III and Complex IV. Because of this shorter path, FADH2 contributes only six protons to membrane transport.

The proton pumping creates a proton motive force. This force includes both a concentration gradient and a voltage gradient across the inner mitochondrial membrane. Protons flow back into the mitochondrial matrix through ATP synthase, a membrane enzyme that uses this energy to make ATP from ADP. This use of the proton motive force is called chemiosmosis.

ATP synthase needs about four protons to produce one ATP molecule. Because NADH and FADH2 move different numbers of protons, they yield different ATP amounts. One NADH molecule produces about 2.5 ATP, while one FADH2 molecule produces about 1.5 ATP. These values show how the electron transport chain links electron flow, proton movement, and cellular energy production.

Electron Transport Chain Powers ATP Output

electron-transport-chain-powers-atp-output

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chemiosmosis and atp synthesis

The electron transport chain powers ATP production during cellular respiration. It sits in the inner mitochondrial membrane and moves high-energy electrons from NADH and FADH2 to molecular oxygen, the final electron acceptor. As electrons move through the chain, protons are pushed across the membrane to build the gradient needed for ATP synthesis. Electrons from NADH enter the chain at Complex I, also called NADH: ubiquinone oxidoreductase. In prokaryotes, this step helps pump protons from the...

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key terms and concepts

Learn how the electron transport chain moves electrons, pumps protons, and drives ATP synthase to make ATP from NADH and FADH2 in cellular respiration.

Electron Transport Chain Powers ATP Output | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

microbiology

Electron Transport Chain Powers ATP Output

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