Chapter 2: Chemistry of Life

The chapter discusses how atoms achieve stability through bonding, categorizing interactions by strength from strongest to weakest: covalent bonds involving shared electron pairs that may be polar or nonpolar, ionic bonds formed through electron transfer, hydrogen bonds, and van der Waals forces. Chemical reactions fundamental to life are explored, including dehydration synthesis as an anabolic process that assembles polymers by removing water molecules, contrasted with hydrolysis as a catabolic reaction that breaks polymers by incorporating water. Redox reactions, which involve electron transfer where oxidation represents electron loss and reduction represents electron gain, are presented as critical to cellular metabolism. The discussion of inorganic compounds centers on water as the universal biological solvent and examines tonicity concepts such as isotonic, hypertonic, and hypotonic conditions that affect cellular behavior. Acid-base chemistry is covered through the pH scale, a logarithmic measurement of hydrogen ion concentration, and the role of buffers in maintaining biological pH stability. The chapter concludes with comprehensive coverage of the four major organic molecules, all characterized by hydrocarbon frameworks: carbohydrates functioning in energy and structural roles; proteins composed of amino acids with complex three-dimensional structures that determine function and can be altered through denaturation; lipids as hydrophobic molecules including triglycerides, phospholipids, and cholesterol that provide energy and membrane components; and nucleic acids such as DNA and RNA that store and express genetic information, along with adenosine triphosphate as the cell's primary energy molecule.