Book excerpt: Comparative Biochemistry: A Comprehensive Treatise, Volume V: Constituents of Life—Part C focuses on the structure and distribution of amino acids, distribution and metabolism of inorganic nitrogen compounds, acid metabolism, and comparative biochemistry of halides. The selection first offers information on the structure and distribution of amino acids and the distribution and metabolism of inorganic nitrogen compounds. Discussions focus on proteinogenous amino acids, nonproteinogenous amino acids, general aspects of inorganic nitrogen metabolism, and distribution and metabolism of nitrate, nitrite, and molecular nitrogen, ammonia, and hydrazine. The text then tackles citric acid cycle and other cycles and comparative biochemistry of collagen. The publication examines photosynthesis and halides. Topics include transfer of energy along the photosynthetic chain, carbon dioxide reduction, photosynthesis and phosphorylation, quantum yields and the efficiency of light energy conversion, chlorine, bromine, and iodine. The selection is a dependable source of data for readers interested in the constituents of life.