Exploring how cell metabolism can be understood in terms of the structure and function of subcellular components, this book describes the structure and function of the major cell organelles and, moving further down in scale, that of the main classes of biological macromolecules. The key role of enzymes in facilitating metabolism is explored and, finally, there is an examination of the structure of the cell membrane. This is part of a series of texts aimed mainly at undergraduates, but they are also suitable for S Level students of biology.