2. Water, lipids, and carbohydrates

This chapter discusses some simpler but no less important molecules: water, lipids, carbohydrates, and nucleotides. These molecules form the physical structures that bound cells and the medium in which the very chemistry of life takes place. Water’s structure and composition allows it to participate makes it a polar molecule and an astonishingly good solvent. Meanwhile, lipids play three main roles in biochemistry: energy storage, signalling, and structure formation. Finally, carbohydrates provide the fuel that powers cells; they form the scaffolding around which so many structures are built; and they frequently embellish proteins, modifying their behaviours or adding functionality.