The document discusses the major biological molecules that make up living things: proteins, carbohydrates, lipids, and nucleic acids. Proteins are made of amino acids and are essential for cell structure, regulation, and transport. Carbohydrates include sugars and starches and serve as energy sources and building materials. Lipids are fats, steroids, and phospholipids that store energy, cushion organs, and make up cell membranes. Nucleic acids DNA and RNA carry genetic instructions and facilitate protein synthesis.