Name: how triglycerides fuel atp production
Uploaded: 2023-04-30T10:41:29.000Z
Duration: 1 min 6 s
Channel: JoVE

Fettsäuren - die Bausteine der Fette, werden als Triglyceride gespeichert, eine langfristige Energiereserve.
In Pflanzen werden Triglyceride produziert und im Inneren des Chloroplasten gespeichert. Pflanzensamen sind besonders reich an Triglyceriden, um den Embryo bis zur Keimung mit Nährstoffen zu versorgen.
Bei Tieren werden sie als Lipidtröpfchen im Zytoplasma spezialisierter Zellen, den Adipozyten, gespeichert.
Bei der Nährstofflimitierung werden bei der Lipolyse die Triglyceride in Fettsäuren und Glycerin zerlegt.
Die resultierenden Fettsäuren werden dann durch β-Oxidation oxidiert, um Acetyl-Coenzym A zu erzeugen, das dann oxidiert wird, um ATP zu produzieren.
Im Gegensatz zu Pflanzen, bei denen die β-Oxidation nur in Peroxisomen vorkommt, kann sie bei Tieren sowohl in Mitochondrien als auch in Peroxisomen vorkommen.
Fette dienen als bessere Energiespeicher als Zucker wie Glykogen, da bei der Oxidation von einem Gramm Fett etwa die doppelte Energie von einem Gramm Glykogen freigesetzt wird.

fette als energiespeichermoleküle

Fats as Energy Storage Molecules

Triglyceride sind eine Form von Molekülen zur langfristigen Energiespeicherung. Sie bestehen aus Glycerin und drei Fettsäuren. Um aus Fett Energie zu gewinnen, müssen Triglyceride zunächst durch Hydrolyse in ihre beiden Hauptbestandteile Fettsäuren und Glycerin zerlegt werden. Dieser Prozess, Lipolyse genannt, findet im Zytoplasma statt. Die resultierenden Fettsäuren werden durch β-Oxidation zu Acetyl-CoA oxidiert, das vom Krebszyklus verwendet wird. Das Glycerin, das nach der Lipolyse aus Triglyceriden freigesetzt wird, gelangt als DHAP direkt in den Glykolyseweg. Da aus einem Triglyceridmolekül drei Fettsäuremoleküle mit jeweils bis zu 16 oder mehr Kohlenstoffatomen entstehen, liefern Fettmoleküle mehr Energie als Kohlenhydrate und sind eine wichtige Energiequelle für den menschlichen Körper. Im Vergleich zu Kohlenhydraten und Proteinen liefern Triglyceride mehr als die doppelte Energie pro Masseneinheit. Daher können Triglyceride bei niedrigem Glukosespiegel in Acetyl-CoA-Moleküle umgewandelt und zur Erzeugung von ATP durch aerobe Atmung verwendet werden.

Der Abbau von Fettsäuren, Fettsäureoxidation oder Beta(β)-Oxidation genannt, beginnt im Zytoplasma, wo Fettsäuren in Fettacyl-CoA-Moleküle umgewandelt werden. Dieses Fettacyl-CoA verbindet sich mit Carnitin und bildet ein Fettacylcarnitinmolekül, das dabei hilft, die Fettsäure durch die Mitochondrienmembran zu transportieren. Sobald es sich in der mitochondrialen Matrix befindet, wird das Fett-Acylcarnitin-Molekül wieder in Fett-Acyl-CoA und dann in Acetyl-CoA umgewandelt. Das neu gebildete Acetyl-CoA tritt in den Krebszyklus ein, um reduzierte Coenzyme zu produzieren, die dann in der Elektronentransportkette zur Produktion von ATP verwendet werden.

Dieser Text ist adaptiert von <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/24-3-lipid-metabolism">Openstax, Biology 2e, Section 24.3:Lipid metabolism</a>

Fette als Energiespeichermoleküle

Triglyceride sind eine Form von Langzeit-Energiespeichermolekülen. Sie bestehen aus Glycerin und drei Fettsäuren. Um Energie aus Fett zu gewinnen, können Triglyceride ...

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how triglycerides fuel atp production

Triglycerides store long-term energy in fats. A triglyceride is built from glycerol and three fatty acids. When the body needs energy, these molecules are broken down first.

This breakdown is called lipolysis, and it happens in the cytoplasm by hydrolysis. Lipolysis splits triglycerides into fatty acids and glycerol. The glycerol then enters glycolysis as DHAP, which connects fat breakdown to the cell’s main energy pathway.

The fatty acids are then oxidized by beta-oxidation into acetyl-CoA. Before they can cross into the mitochondrion, the fatty acids are changed into fatty acyl-CoA. They then bind to carnitine to form fatty acylcarnitine, which helps move them across the mitochondrial membrane. Inside the mitochondrial matrix, they are converted back to fatty acyl-CoA and then to acetyl-CoA.

Acetyl-CoA enters the Krebs cycle and helps produce reduced coenzymes. These coenzymes feed the electron transport chain, where ATP is made through aerobic respiration. Because one triglyceride can release three fatty acids with 16 or more carbons each, fats provide more than twice the energy per unit mass than carbohydrates and proteins. That is why triglycerides are a major energy source when glucose levels are low.

How Triglycerides Fuel ATP Production

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fats as energy storage molecules

Triglycerides store long-term energy in fats. A triglyceride is built from glycerol and three fatty acids. When the body needs energy, these molecules are broken down first. This breakdown is called lipolysis, and it happens in the cytoplasm by hydrolysis. Lipolysis splits triglycerides into fatty acids and glycerol. The glycerol then enters glycolysis as DHAP, which connects fat breakdown to the cell’s main energy pathway. The fatty acids are then oxidized by beta-oxidation into acetyl-CoA.

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Learn how triglycerides are broken down into fatty acids and glycerol, then used to make acetyl-CoA and ATP when glucose is low.

How Triglycerides Fuel ATP Production | JoVE K12

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How Triglycerides Fuel ATP Production

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