The intermediary metabolism of small molecules is a fundamental of cell function. The pathways and modes of obtaining energy, degradation and utilization of exogenous organic nutrients, and formation of the building blocks of the main macromolecules were a major focus of research in biology from the turn of the 20th century into the 1970s. Other matters have come to prominence, but the field is active, with interesting problems that are central to biology and medicine.
Molecular biology developed through the use of one bacterium, Eschericha coli; in recent years, an analogous workhorse has been the eukaryotic microbe baker's yeast, Saccharomyces cerevisiae, used in many studies of cell biology common to multicellular organisms. This book explains metabolism as based on Saccharomyces.