Machine generated contents note: Chapter 1. Introduction and general aspects, chemistry and physical chemistry Gerhard Michael and Dietmar Schomburg Chapter 2. The cell and its contents: Enzymes, nucleic acids, and polymeric carbohydrates and lipids Gerhard Michal and Dietmar Schomburg Chapter 3. General metabolism in animals, plants and bacteria 3.1 Carbohydrate Metabolism and Citrate Cycle 3.2 Amino Acids and Derivatives 3.3 Tetrapyrroles 3.4 Lipids amd Glycolipids 3.5 Steriods and Isopreniods 3.6 Nucleotides and Nucleosides 3.7 Cofactors and Vitamins