Chapter 2: Cell Chemistry and Bioenergetics

Cell Chemistry and Bioenergetics begins with a breakdown of atoms, covalent bonds, and the role of carbon in building the diverse molecules essential for life. The chapter describes water as a universal solvent, explaining hydrogen bonding, hydrophobic effects, and how these contribute to the behavior of macromolecules. Four major families of small organic molecules—sugars, fatty acids, amino acids, and nucleotides—are introduced, with emphasis on how these serve as building blocks for polysaccharides, fats, proteins, and nucleic acids. The structure and formation of macromolecules through condensation reactions and their degradation by hydrolysis are explored, along with the concepts of directionality and polymer sequence as carriers of information and function. The chapter also explains the physical forces that determine macromolecular shape, such as noncovalent bonds and van der Waals attractions, and how these enable specific molecular interactions essential for enzyme-substrate binding and protein folding. In the section on bioenergetics, the text dives into the principles of thermodynamics, particularly how cells harness chemical reactions to drive energetically unfavorable processes. It covers free energy (ΔG), activation energy, and the critical role of enzymes in lowering energy barriers. The role of ATP as an energy currency is emphasized, along with how cells couple reactions to maintain order and carry out mechanical, chemical, and transport work. Finally, the chapter concludes by reinforcing how the principles of chemistry govern biological systems, enabling the complexity and specificity of cellular life.