Biological Macromolecules: Structure and Function
Carbohydrates come in three main forms, each with unique roles in organisms. Monosaccharides are simple sugars (like glucose) that provide quick energy for cells. When two monosaccharides join through a glycosidic linkage, they form disaccharides like sucrose or lactose. Polysaccharides like starch and cellulose contain many sugar units linked together and serve as energy storage or structural support.
The type of glycosidic linkage matters biologically! Starch contains alpha linkages that most organisms can digest, while cellulose has beta linkages that humans can't break down. This simple structural difference explains why we can digest potato starch but not the cellulose in lettuce.
Lipids form another major macromolecule group with various functions. Triglycerides store energy, phospholipids form cell membranes, and steroids like cholesterol regulate body processes. Lipids can be classified as saturated (no double bonds), unsaturated (one or more double bonds), or trans fats (artificially modified unsaturated fats).
Fun Fact: The reason butter (high in saturated fats) is solid at room temperature while olive oil (high in unsaturated fats) is liquid relates directly to their molecular structure!
The four major classes of macromolecules in living organisms are carbohydrates, lipids, proteins, and nucleic acids. These large molecules are built from smaller subunits called monomers, which link together to form polymers through dehydration synthesis reactions (where water is removed).