📖 2. Water

📖 From Principles of Biochemistry • 319 questions available

About 2. Water

Water is far more than a passive solvent; it is the active chemical medium that shapes nearly every aspect of biochemistry. This chapter opens by examining the structure of the water molecule, focusing on its bent geometry and polar covalent bonds, which give rise to hydrogen bonding between water molecules. These weak, dynamic interactions are responsible for water's unique physical properties—cohesion, surface tension, high specific heat, and high heat of vaporization—all of which are essential for temperature regulation and cellular stability. The chapter then explains how water's polarity makes it an excellent solvent for polar and charged molecules (hydrophilic substances), while nonpolar molecules (hydrophobic) are forced to interact differently, driving crucial phenomena like micelle formation and membrane assembly.

Moving deeper into biochemistry, the chapter explores how water participates directly in chemical reactions, including hydrolysis and dehydration synthesis, which are fundamental to building and breaking down macromolecules. A central topic is the concept of pH, defined as the negative logarithm of hydrogen ion concentration, and the dissociation of water into H⁺ and OH⁻ ions. The chapter thoroughly covers weak acids and bases, the Henderson-Hasselbalch equation, and the critical role of buffers in maintaining the narrow pH range required for enzyme function and metabolic processes. Special attention is given to physiological buffers, such as the bicarbonate system in blood, and how disruptions in pH can lead to conditions like acidosis or alkalosis. By understanding water's chemistry, students gain the foundation for interpreting all subsequent topics, from protein folding to energy metabolism.

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🔄 Last updated: 2026-09-14