Name: cellular respiration: atp production pathways
Uploaded: 2025-06-12T09:34:08.000Z
Duration: 1 min 18 s
Channel: JoVE

Die Zellatmung ist ein biochemischer Prozess, bei dem ATP durch die Oxidation von Molekülen unter Verwendung eines externen Elektronenakzeptors erzeugt wird. Es beginnt mit der Glykolyse, bei der Glukose in Pyruvat umgewandelt wird, während ATP und NADH produziert werden. Pyruvat tritt in den Krebszyklus ein, kommt im Zytoplasma von Prokaryoten oder in der mitochondrialen Matrix von Eukaryoten vor und erzeugt NADH2. Elektronen von diesen Trägern durchlaufen die Elektronentransportkette, die sich in der Plasmamembran von Prokaryoten und der inneren Mitochondrienmembran von Eukaryoten befindet, und produzieren ATP durch oxidative Phosphorylierung. Bei der aeroben Atmung wird Sauerstoff als Elektronenakzeptor verwendet und kann in Prokaryoten bis zu 38 ATP pro Glukosemolekül produziert werden. In Eukaryoten liegt die Nettoausbeute bei etwa 30 bis 32 ATP, da beim Pendeln von NADH etwas Energie verbraucht wird. Einige Prokaryoten und Eukaryoten durchlaufen eine anaerobe Atmung, bei der alternative Elektronenakzeptoren wie Nitrat oder Sulfat als Elektronenakzeptor mit geringeren ATP-Ausbeuten verwendet werden.

atmung

Cellular Respiration

Die Zellatmung ist ein entscheidender metabolischer Prozess, durch den Zellen Energie aus organischen Substanzen, haupts&#228;chlich Glukose, gewinnen, um Adenosintriphosphat (ATP) zu produzieren. Dieser Prozess umfasst die Oxidation von Substraten und die &#220;bertragung von Elektronen auf einen separaten Elektronenakzeptor, wodurch durch eine Abfolge biochemischer Reaktionen die ATP-Synthese erm&#246;glicht wird.
Glykolyse: Der erste Schritt
Die Glykolyse stellt die initiale Phase der Zellatmung dar und findet im Zytoplasma von sowohl prokaryotischen als auch eukaryotischen Zellen statt. Dabei wird ein Molek&#252;l Glukose (C_6H_12O_6) in zwei Molek&#252;le Pyruvat (C_3H_4O_3) gespalten, wobei ein Nettogewinn von 2 ATP und 2 NADH entsteht. Dieser Prozess erfordert keinen Sauerstoff und dient als vorbereitender Schritt sowohl f&#252;r die aerobe als auch f&#252;r die anaerobe Atmung.
Der Citratzyklus: Erzeugung von Elektronentransporttr&#228;gern
Pyruvat unterliegt einem entscheidenden Prozess, der als Decarboxylierung bekannt ist, wobei es in Acetyl-CoA umgewandelt wird. Dieses neu gebildete Acetyl-CoA tritt dann in den Citratzyklus ein, der auch als Zitronens&#228;urezyklus oder Tricarbons&#228;urezyklus bezeichnet wird. Diese komplexe Reihe biochemischer Reaktionen findet im Zytoplasma von Prokaryoten und in der mitochondrialen Matrix von Eukaryoten statt.
W&#228;hrend Acetyl-CoA durch den Citratzyklus gef&#252;hrt wird, spielt es eine zentrale Rolle bei der Energiegewinnung. F&#252;r jedes verarbeitete Molek&#252;l Acetyl-CoA entstehen drei Molek&#252;le NADH, ein Molek&#252;l FADH_2 und ein GTP. Diese Elektronentransporttr&#228;ger, NADH und FADH_2, sind entscheidend f&#252;r die anschlie&#223;ende ATP-Synthese. Zus&#228;tzlich wird Kohlendioxid (CO_2) als Nebenprodukt freigesetzt, was zur allgemeinen Stoffwechselaktivit&#228;t der Zelle beitr&#228;gt.
Elektronentransportkette und oxidative Phosphorylierung
Die Elektronentransportkette (ETC) befindet sich in der Plasmamembran von Prokaryoten, w&#228;hrend sie bei Eukaryoten in der inneren Mitochondrienmembran lokalisiert ist. Elektronen aus NADH und FADH_2 werden durch eine Reihe von Proteinkomplexen geleitet, wodurch ein Protonengradient &#252;ber die Membran hinweg erzeugt wird. Der R&#252;ckfluss der Protonen durch die ATP-Synthase treibt die Phosphorylierung von ADP zu ATP an. Im Rahmen der aeroben Atmung dient Sauerstoff als terminaler Elektronenakzeptor, wobei Wasser (H_2O) entsteht.
ATP-Ausbeute und alternative Elektronenakzeptoren
Die aerobe Atmung kann in Prokaryoten bis zu 38 ATP-Molek&#252;le pro Glukosemolek&#252;l liefern, w&#228;hrend die Netto-ATP-Produktion bei Eukaryoten bei etwa 30&#8211;32 liegt, bedingt durch Energieverluste beim Transport von NADH in die Mitochondrien. Bei der anaeroben Atmung verwenden Prokaryoten und einige Eukaryoten alternative Elektronenakzeptoren wie Nitrat (NO_3^-), Sulfat (SO_4^2-) oder Kohlendioxid (CO_2), was zu einer deutlich geringeren ATP-Ausbeute f&#252;hrt &#8211; typischerweise etwa 2 ATP pro Glukose &#8211; aufgrund der geringeren Effizienz dieser Elektronenakzeptoren bei der Erzeugung eines Protonengradienten.
Die Zellatmung ist wesentlich f&#252;r den Energiestoffwechsel, da sie es Organismen erm&#246;glicht, durch ATP-Produktion ihre zellul&#228;ren Funktionen aufrechtzuerhalten. Die Effizienz und Auswahl des Elektronenakzeptors bestimmen die Energieausbeute und die metabolischen Anpassungen verschiedener Organismen an unterschiedliche Umweltbedingungen.

Atmung

Die Zellatmung ist ein entscheidender metabolischer Prozess, durch den Zellen Energie aus organischen Substanzen, haupts&#228;chlich Glukose, gewinnen, um ...

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cellular respiration: atp production pathways

Cellular respiration is the process cells use to turn glucose into ATP, the main energy molecule in the cell. It depends on oxidation and the transfer of electrons to a separate electron acceptor. This sequence of reactions supports energy production in both aerobic and anaerobic settings.

Glycolysis is the first step. It takes place in the cytoplasm of both prokaryotic and eukaryotic cells. One glucose molecule is broken into two pyruvate molecules, and the cell gains a net 2 ATP and 2 NADH. Glycolysis does not require oxygen, so it can support both aerobic and anaerobic respiration.

Pyruvate then undergoes decarboxylation and becomes acetyl-CoA. Acetyl-CoA enters the Krebs cycle, also called the citric acid cycle or tricarboxylic acid cycle. In prokaryotes, this cycle occurs in the cytoplasm. In eukaryotes, it occurs in the mitochondrial matrix. Each acetyl-CoA produces 3 NADH, 1 FADH2, and 1 GTP. The cycle also releases carbon dioxide as a byproduct.

The electron transport chain, or ETC, uses the NADH and FADH2 made earlier. In prokaryotes, the ETC is in the plasma membrane. In eukaryotes, it is in the inner mitochondrial membrane. Electrons move through protein complexes and create a proton gradient across the membrane. ATP synthase uses the return flow of protons to convert ADP into ATP. In aerobic respiration, oxygen is the final electron acceptor, and water forms.

Aerobic respiration can yield up to 38 ATP per glucose in prokaryotes. In eukaryotes, the net yield is about 30 to 32 ATP because energy is used to move NADH into mitochondria. Some organisms also use anaerobic respiration. In that pathway, alternative electron acceptors such as nitrate, sulfate, or carbon dioxide are used. This form makes much less ATP, usually around 2 ATP per glucose, because these acceptors build a weaker proton gradient. Cellular respiration is therefore essential for ATP production and for the energy metabolism that keeps cells functioning.

Cellular Respiration: ATP Production Pathways

cellular-respiration-atp-production-pathways

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cellular respiration

Cellular respiration is the process cells use to turn glucose into ATP, the main energy molecule in the cell. It depends on oxidation and the transfer of electrons to a separate electron acceptor. This sequence of reactions supports energy production in both aerobic and anaerobic settings. Glycolysis is the first step. It takes place in the cytoplasm of both prokaryotic and eukaryotic cells. One glucose molecule is broken into two pyruvate molecules, and the cell gains a net 2 ATP and 2 NADH.

electron transport chain components

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Electron Transport Chain Powers ATP Output

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key terms and concepts

Learn how cells make ATP through glycolysis, the Krebs cycle, and the electron transport chain, plus how aerobic and anaerobic respiration differ.

Cellular Respiration: ATP Production Pathways | 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

Cellular Respiration: ATP Production Pathways

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