Polisakaridi

Polisakaridi is the term used in Greek to refer to polysaccharides, a broad class of carbohydrates composed of long chains of monosaccharide units joined by glycosidic bonds. The chains can contain thousands of sugar units and vary in monomer composition, linkage type, and branching. As a group, polisakaridi serve diverse roles in biology and industry, including energy storage, structural support, and as texturizing agents.

Classification of polisakaridi is commonly by monomer type (homopolysaccharides vs heteropolysaccharides), by structure (linear vs branched), and by the type of glycosidic bonds (alpha or beta). These features influence properties such as solubility, digestibility, and mechanical strength.

Examples include starch and glycogen, glucose-based energy-storage polysaccharides in plants and animals; starch comprises amylose (mostly linear) and amylopectin (branched). Structural polysaccharides include cellulose in plant cell walls and chitin in arthropod exoskeletons. Other polysaccharides, such as pectin, agar, alginates, and gums, act as gelling, thickening, or stabilizing agents in foods and industrial applications.

Biochemically, polisakaridi are synthesized by cells through glycosyltransferases and degraded by hydrolytic enzymes such as amylases and cellulases. In nutrition, polysaccharides may provide energy (as in starch), contribute dietary fiber (certain non-digestible polysaccharides), or play structural and functional roles in organisms and products.