MCAT Biochemistry
Storage lipids, also known as triglycerides, serve as long-term energy storage and insulation in the body. Triglycerides, or triacylglycerols, are composed of three fatty acids bonded by ester linkages to glycerol. In animals, they are stored in cells called adipocytes, which are found in adipose tissue. Triglyceride catabolism is catalyzed by lipases, generating glycerol and free fatty acids.
Scientists (and soap makers) can break the ester bonds of triglycerides through a process called saponification, requiring water and a strong base like sodium hydroxide or potassium hydroxide. Saponification results in glycerol and amphipathic fatty acid salts, which are known as soaps. In water, fatty acid salt molecules form micelles, structures that allow for the solvation of hydrophobic substances inside of them. Micelles also play a role in the body during lipid absorption and digestion.
Lesson Outline
<ul> <li>Function of storage lipids</li> <ul> <li>Long-term energy storage</li> <li>Insulation</li> </ul> <li>Triglycerides</li> <ul> <li>Composition: three fatty acids bonded to glycerol</li> <li>Stored in adipocytes</li> <li>Found in adipose tissue</li> </ul> <li>Triglyceride catabolism</li> <ul> <li>Catalyzed by lipases</li> <li>Generates glycerol and free fatty acids</li> </ul> <li>Saponification</li> <ul> <li>Outside the body process</li> <li>Requires water and strong base</li> <li>Results in glycerol and amphipathic fatty acid salts</li> </ul> <li>Soap and micelles</li> <ul> <li>Salts of fatty acids</li> <li>Surfactant properties</li> <li>Micelle formation in water</li> <li>Solvation of hydrophobic substances</li> </ul> </ul>
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FAQs
Storage lipids are molecules that store energy in the form of fatty acids within organisms. Triacylglycerols, also known as triglycerides, are the primary storage lipids found in animals and some plants. They are composed of a glycerol molecule and three fatty acid molecules, which can be released and utilized as energy when needed. Triacylglycerols are stored in specialized cells called adipocytes and provide both insulation and a long-term energy reserve for the organism.
Triacylglycerols, or triglycerides, are storage lipids that consist of a glycerol molecule connected to three fatty acid molecules by ester bonds. They are relatively non-polar and insoluble in water. In contrast, free fatty acids are individual fatty acid molecules that are not bound to glycerol. They have a carboxyl group (-COOH) at one end, making them more polar and slightly soluble in water. Free fatty acids can be utilized as a source of energy or serve as building blocks for other molecules in the body.
Saponification is the process of hydrolyzing the ester bonds of a triglyceride with the addition of a strong base, such as sodium hydroxide. This reaction results in the formation of glycerol and a fatty acid salt, commonly referred to as soap. In relation to storage lipids, saponification provides a way to break down triacylglycerols, converting them into their individual components – glycerol and free fatty acids – which can then be used for various purposes, including energy production and synthesis of other molecules.
Triacylglycerols are broken down through a process called lipolysis, which involves the hydrolysis of the ester bonds between glycerol and fatty acids. Lipases are enzymes that catalyze this hydrolysis, effectively breaking down triglycerides into free fatty acids and glycerol. These free fatty acids and glycerol can then be transported to different tissues in the body and utilized as energy or as precursors for the synthesis of other molecules.
Micelles are spherical structures formed by amphiphilic molecules like bile salts and phospholipids in aqueous solutions, such as the watery environment of the small intestine. The hydrophobic (water-repellent) tails of these molecules point inward, while the hydrophilic (water-attracting) heads point outward, effectively encapsulating hydrophobic substances, like triacylglycerols and other dietary lipids. Micelles facilitate the absorption of lipids by transporting them to the surface of the intestinal cells (enterocytes) where they can be absorbed and further processed for transport to other tissues in the body.
