The document summarizes the key components that make up cells. It describes the five major classes of molecules that cells are made of: water, carbohydrates, lipids, proteins, and nucleic acids. Each class is comprised of smaller molecules that serve important functions. For example, carbohydrates include simple sugars, complex starches and structural cellulose. Lipids encompass fats, oils, and phospholipids that make up cell membranes. Proteins have complex structures and serve as enzymes, hormones, and structures. Nucleic acids like DNA and RNA contain the cell's genetic code.