TABLE OF CONTENTS Biomolecules are those compounds synthesized by living organisms. These groups of compounds have different sizes, shapes, chemical and physical properties, and biological functions. These biomolecules include different classes of compounds, which are broadly divided into two categories, depending on size and nature. Those molecules, which are polymers and bigger in size, are known as macromolecules and other molecules, which are simple and small in size, are biomolecules. There are four types of macromolecules in biological systems; namely, carbohydrates, proteins, lipids, and nucleic acids. Out of these four types three are polymers composed of monomers, or building blocks. Lipids are not polymers.
This part is divided into three chapters. In the first chapter we study the small molecules including the building blocks of macromolecules. This includes monosaccharides or sugars, amino acids, nucleotides, vitamins, coenzymes, and fatty acids. Some of these molecules form the building blocks of macromolecules. For example, amino acids are the building blocks of proteins. In biological systems, all these molecules, both macro and micro, are in a state of flux or in a dynamic state. That is, they are always subjected to chemical transformations in order to maintain the state of life. Actually, the sum total of all these biochemical changes forms the metabolism of an organism. These metabolic reactions are interconnected and arranged into specific metabolic pathways, and they may be linear or cyclic.
