BIOCHEMISTRY - Textbook - Ostapchenko L. I. - 2012

Chapter 11. STRUCTURE AND PROPERTIES OF CARBOHYDRATES

CARBOHYDRATES are the most abundant organic molecules in nature, being essential components of Cells and Tissues in All living organisms and accounting for the bulk of planetary biomass. The carbohydrate content in biological tissues ranges from 2% in animals to 80% of the dry weight in plants. They are synthesized by green plants and other photosynthetic organisms from Inorganic Compounds—carbon dioxide and Water—According to the equation:

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Photosynthesis transforms the energy of solar electromagnetic radiation into the chemical bond energy of carbohydrate hydrate molecules, amounting to 4.69· 10⁵ J of energy per gram-molecule. Carbohydrates—the primary products of photosynthesis—serve as precursors for all Organic compounds involved in vital life processes. They are key Structural components of NUCLEOTIDES, Nucleic Acids, Glycoproteins, Proteoglycans, Glycolipids, and other biologically active molecules. Carbohydrates perform structural Functions in The Cell walls of plants, Fungi, and microorganisms, as well as in cell coats and the Extracellular matrix of animal tissues. Furthermore, they play a crucial energy-supplying role for non-photosynthetic organisms. In the human daily diet, for instance, carbohydrates account for 400-500 g, which is equivalent to ~9.211·10³ kJ of metabolic energy. In addition, they provide a protective function as constituents of saliva, the mucosal lining of The Stomach and intestines, intercellular fluids, and other bodily secretions.

The vast majority of carbohydrates are compounds of carbon, hydrogen, and oxygen conforming to the empirical formula (СН₂О)n, which justifies the name "carbohydrates"; however, it should be noted that certain compounds deviate from this traditional naming convention in both composition and elemental ratio.

Depending on their composition, Structure, and properties—particularly their susceptibility to Hydrolysis—carbohydrates are classified into three major groups: Monosaccharides, Oligosaccharides, and Polysaccharides.