Cells are incredibly complex and diverse structures, capable not only of self-replicationthe very essence of lifebut also of performing a wide range of specialized tasks in multicellular organisms. Yet cells obey the same laws of chemistry and physics that determine the behavior of nonliving systems. Consequently, modern cell biology seeks to understand cellular processes in terms of chemical and physical reactions.

This chapter considers the fundamental principles of biological chemistry that govern the lives of cells. It is intended neither to be a comprehensive discussion of biochemistry nor to chart all the metabolic reactions within cells. Rather, the chapter will focus on five major topics: the types of molecules within cells, the central role of proteins as biological catalysts, the generation and utilization of metabolic energy, the biosynthesis of major cell constituents, and the structure of biological membranes. An appreciation of these chemical foundations forms the basis for understanding the diverse aspects of cell structure and function that will be discussed throughout the rest of this text.