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

Gli acidi grassi, i mattoni dei grassi, sono immagazzinati come trigliceridi, una riserva di energia a lungo termine.
Nelle piante, i trigliceridi vengono prodotti e immagazzinati all'interno del cloroplasto. I semi delle piante sono particolarmente ricchi di trigliceridi per fornire nutrimento all'embrione fino alla sua germinazione.
Negli animali, sono immagazzinati come goccioline lipidiche nel citoplasma di cellule specializzate chiamate adipociti.
Durante la limitazione dei nutrienti, la lipolisi scompone i trigliceridi in acidi grassi e glicerolo.
Gli acidi grassi risultanti vengono quindi ossidati mediante β-ossidazione per produrre acetil coenzima A, che viene poi ossidato per produrre ATP.
A differenza delle piante in cui la β-ossidazione si verifica solo nei perossisomi, può verificarsi sia nei mitocondri che nei perossisomi negli animali.
I grassi fungono da migliori riserve di energia rispetto allo zucchero come il glicogeno perché l'ossidazione di un grammo di grasso rilascia circa il doppio dell'energia di un grammo di glicogeno.

grassi come molecole di accumulo di energia

Fats as Energy Storage Molecules

I trigliceridi sono una forma di molecole di accumulo di energia a lungo termine. Sono costituiti da glicerolo e tre acidi grassi. Per ottenere energia dai grassi, i trigliceridi devono prima essere scomposti mediante idrolisi nei loro due componenti principali, acidi grassi e glicerolo. Questo processo, chiamato lipolisi, avviene nel citoplasma. Gli acidi grassi risultanti vengono ossidati mediante β-ossidazione in acetil-CoA, che viene utilizzato dal ciclo di Krebs. Il glicerolo che viene rilasciato dai trigliceridi dopo la lipolisi entra direttamente nella via della glicolisi come DHAP. Poiché una molecola di trigliceridi produce tre molecole di acidi grassi con fino a 16 o più atomi di carbonio in ciascuna, le molecole di grasso producono più energia dei carboidrati e sono un'importante fonte di energia per il corpo umano. I trigliceridi producono più del doppio dell'energia per unità di massa rispetto ai carboidrati e alle proteine. Pertanto, quando i livelli di glucosio sono bassi, i trigliceridi possono essere convertiti in molecole di acetil-CoA e utilizzati per generare ATP attraverso la respirazione aerobica.

La scomposizione degli acidi grassi, chiamata ossidazione degli acidi grassi o beta (β)-ossidazione, inizia nel citoplasma, dove gli acidi grassi vengono convertiti in molecole grasse acil-CoA. Questo acil-CoA grasso si combina con la carnitina per creare una molecola grassa di acilcarnitina, che aiuta a trasportare l'acido grasso attraverso la membrana mitocondriale. Una volta all'interno della matrice mitocondriale, la molecola grassa di acilcarnitina viene riconvertita in acil-CoA grasso e poi in acetil-CoA. L’acetil-CoA appena formato entra nel ciclo di Krebs per produrre coenzimi ridotti, che vengono poi utilizzati nella catena di trasporto degli elettroni per produrre ATP.

Questo testo è adattato da <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/24-3-lipid-metabolism">Openstax, Biology 2e, Section 24.3:Lipid metabolism</a>

Grassi come molecole di accumulo di energia

I trigliceridi sono una forma di molecole di accumulo di energia a lungo termine. Sono fatti di glicerolo e tre acidi grassi. Per ottenere energia dai grassi, i trigliceridi ...

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Cell Biology

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Unit 1

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Introduction to Metabolism

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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

overview of metabolism

Metabolism in Plants, Animals, and Microbes

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Electron Carriers in Cellular Energy

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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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key terms and concepts

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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