Topic overview

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Lipids contain mainly carbon, hydrogen, and oxygen, with some classes also containing phosphorus, nitrogen, or sulfur. They are grouped as simple, compound, or derived lipids, including triacylglycerols, phospholipids, fatty acids, and sterols. Fatty acids vary in saturation, and essential fatty acids must be obtained from the diet. Triacylglycerols serve as an energy reserve, while phospholipids help form membranes and cholesterol contributes to membrane properties and acts as a precursor for several substances. Amphipathic lipids can organize into micelles and bilayers. The topic also introduces lipid digestion, transport in lipoproteins, fatty-acid breakdown, lipid synthesis, and ketone-body production, showing how lipid chemistry relates to physiology.