Learn: Lipids - Triglycerides, Phospholipids, and Tests

Welcome!You've already studied biological molecules like carbohydrates and their important roles. Now, let's explore lipids, another essential group of biological molecules. We'll learn about triglycerides, phospholipids, and how we test for their presence.

What are Lipids?Lipids are non-polar molecules made mainly of carbon, hydrogen, and oxygen. They include triglycerides, phospholipids, and steroids, and are important for energy storage, insulation, and forming cell membranes.

TriglyceridesA triglyceride is made of one glycerol molecule and three fatty acids. These molecules are joined by ester bonds formed during a condensation reaction. Triglycerides are important for long-term energy storage due to their high energy content.

Saturated vs Unsaturated Fatty AcidsFatty acids can be saturated (no double bonds between carbon atoms) or unsaturated (one or more double bonds). Unsaturated fatty acids cause kinks in the chain, making them less compact and liquid at room temperature.

PhospholipidsPhospholipids consist of one glycerol molecule, two fatty acids, and a phosphate group. Their structure makes them ideal for forming cell membranes, with hydrophilic (water-attracting) heads and hydrophobic (water-repelling) tails.

Testing for Lipids: The Emulsion TestThe emulsion test checks for lipids. Mix the sample with ethanol, then add water. A milky white emulsion indicates the presence of lipids.

Review Time!Great work! You've learned about lipids, including triglycerides, phospholipids, and the emulsion test. Let’s check your understanding with some final questions.