Divisions of biochemistry

No rigid, conventional divisions of biochemistry exist, as in the case of chemistry and physics proper, where a distinction between organic' and "inorganic," for example, is rather sharp. Still dominant is the treatment where the class of substance involved is the name of the subject, as "Carbohydrates," "Fats," "Proteins. . . . . Inorganic Constituents," "Accessory Substances," and now '"Hormones." Almost all texts describe these groups of substances and then take up what is known of their ingestion or synthesis in the body, their role, their metabolism and the further course, final consumption and elimination of the products of their metabolism. That at least the principal classes of materials serve as equivalents of one another and are mutually convertible tends to upset any such classification. The latter part of many a text, therefore, resorts to a series of chapters where the physiological process, e.g. digestion, or the function of an important organ, e.g., the kidney or the liver, serves as the division of the subject.

Occasionally a text starts with a phsico-chemical introduction in place of the organic chemistry of the principal materials. In such cases a stress on colloid chemistry is imperative. The fields of biochemistry shape up as applications of sectors of the other sciences to living systems.