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

Fatty acids - the building blocks of fats, are stored as triglycerides, a long term energy reserve.
In plants, triglycerides are produced and stored inside the chloroplast. Plant seeds are particularly rich in triglycerides to provide nutrition to the embryo until it germinates.
In animals, they are stored as lipid droplets in the cytoplasm of specialized cells called adipocytes.
During nutrient limitation, lipolysis breaks down the triglycerides into fatty acids and glycerol.
The resultant fatty acids are then oxidized by &#946;-oxidation to produce acetyl coenzyme A, which is then oxidized to produce ATP.
In contrast to plants where &#946;-oxidation occurs only in peroxisomes, it can occur in both mitochondria and peroxisomes in animals.
Fats serve as better energy reservoirs than sugar such as glycogen because oxidation of one gram of fat releases approximately double the energy of one gram of glycogen.

fats as energy storage molecules

Fats as Energy Storage Molecules

Triglycerides are a form of long-term energy storage molecules. They are made of glycerol and three fatty acids. To obtain energy from fat, triglycerides must first be broken down by hydrolysis into their two principal components, fatty acids and glycerol. This process, called lipolysis, takes place in the cytoplasm. The resulting fatty acids are oxidized by &#946;-oxidation into acetyl-CoA, which is used by the Krebs cycle. The glycerol that is released from triglycerides after lipolysis directly enters the glycolysis pathway as DHAP. Because one triglyceride molecule yields three fatty acid molecules with as much as 16 or more carbons in each one, fat molecules yield more energy than carbohydrates and are an important source of energy for the human body. Triglycerides yield more than twice the energy per unit mass when compared to carbohydrates and proteins. Therefore, when glucose levels are low, triglycerides can be converted into acetyl-CoA molecules and used to generate ATP through aerobic respiration.
The breakdown of fatty acids, called fatty acid oxidation or beta (&#946;)-oxidation, begins in the cytoplasm, where fatty acids are converted into fatty acyl-CoA molecules. This fatty acyl-CoA combines with carnitine to create a fatty acylcarnitine molecule, which helps to transport the fatty acid across the mitochondrial membrane. Once inside the mitochondrial matrix, the fatty acylcarnitine molecule is converted back into fatty acyl-CoA and then into acetyl-CoA. The newly formed acetyl-CoA enters the Krebs cycle to produce reduced coenzymes, which are then used in the electron transport chain to produce ATP.
This text is adapted from <a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/24-3-lipid-metabolism">Openstax, Biology 2e, Section 24.3:</a><a href="https://openstax.org/books/anatomy-and-physiology-2e/pages/24-3-lipid-metabolism">Lipid metabolism</a>

Triglycerides are a form of long-term energy storage molecules. They are made of glycerol and three fatty acids. To obtain energy from fat, triglycerides ...

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JoVE Core

Cell Biology

Unit 1

Introduction to Metabolism

KEY TERMS AND CONCEPTS

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

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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

cell biology

JoVE Core Cell Biology illustrates complex cellular processes in easy-to-understand yet comprehensive animated video lessons. This collection focuses on the essential components and functions of cells, including organelles and membranes, cellular transport, and cell energetics. It is complemented by scientist-in-action videos that demonstrate the application of cell biology in real-world research experiments.

How Triglycerides Fuel ATP Production

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