Polysaccharide is what? The use of polysaccharides and their significance

There are four main classes of complexbioorganic substances: proteins, fats, nucleic acids and carbohydrates. Polysaccharides belong to the latter group. Despite the "sweet" name, most of them perform completely non-culinary functions.

Polysaccharide is what?

The substances of the group are also called glycans. The polysaccharide is a complex polymer molecule. It is made up of individual monomers - monosaccharide residues, which are combined with a glycosidic bond. Simply put, a polysaccharide is a molecule built from the combined remains of simpler carbohydrates. The amount of monomers in a polysaccharide can vary from a few tens to a hundred or more. The structure of polysaccharides can be either linear or branched.

Physical properties

Most polysaccharides are insoluble or poorlyare soluble in water. Most often they are colorless or yellowish. Most polysaccharides do not have a smell and taste, but sometimes it can be sweet.

Basic chemical properties

Among the special chemical properties of polysaccharides, hydrolysis and the formation of derivatives can be identified.

Hydrolysis is a process that occurs whenthe interaction of a carbohydrate with water with the participation of enzymes or catalysts, such as acids. During this reaction, the polysaccharide decomposes into monosaccharides. Thus, it can be said that hydrolysis is a reverse polymerisation process.

The glycolysis of starch can be expressed by the following equation:

(FROM₆H₁₀ABOUT₅)_n + n H₂O = n C₆H₁₂ABOUT₆

So, when starch reacts with water under the action of catalysts, we get glucose. The number of its molecules will be equal to the amount of monomers that formed the molecule of starch.

The formation of derivatives can occur whenreactions of polysaccharides with acids. In this case, carbohydrates add to their residues acids, resulting in the formation of sulfates, acetates, phosphates, etc. In addition, the addition of methanol residues can occur, which leads to the formation of esters.

Biological role

Polysaccharides in the cell and in the body can perform the following functions:

protective;
structural;
stocking;
energy.

The protective function consists, first of all,that the polysaccharides consist of cell walls of living organisms. So, the cell wall of plants consists of cellulose, fungi - from chitin, bacteria - from murein.

In addition, the protective function of polysaccharides inthe human body is expressed in the fact that glands secrete secretions enriched with these carbohydrates, which protect the walls of such organs as the stomach, intestines, esophagus, bronchi, etc. from mechanical damage and penetration of pathogenic bacteria.

The structural function of polysaccharides in a cell is that they are part of the plasma membrane. They are also components of membranes of organelles.

The next function is that the main reserve substances of organisms are exactly polysaccharides. For animals and fungi it is glycogen. In plants, the reserve polysaccharide is starch.

The latter function is expressed in the fact thatpolysaccharide is an important source of energy for the cell. Get it from such a carbohydrate cell can by splitting it into monosaccharides and further oxidizing to carbon dioxide and water. On average, when a single gram of polysaccharide is cleaved, the cell receives 17.6 kJ of energy.

The use of polysaccharides

These substances are widely used in industry and medicine. Most of them are mined in laboratories by polymerization of simple carbohydrates.

The most widely used polysaccharides are starch, cellulose, dextrin, agar-agar.

**The use of polysaccharides in industry**
Name of substance	Using	A source
Starch	It finds application in the food industry. Also serves as raw material for obtaining glucose, alcohol. It is used for making glue, plastics. In addition, it is also used in the textile industry	Obtained from potato tubers, as well as corn, rice, wheat and other starch-rich plants
Cellulose	Used in pulp and paper and textileindustry: it produces cardboard, paper, viscose. Cellulose derivatives (nitro-, methyl-, acetylcellulose, etc.) are widely used in the chemical industry. Of these, synthetic fibers and fabrics, artificial leather, paints, varnishes, plastics, explosives and much more are produced	Obtain this substance from wood, mostly conifers. It is also possible to produce cellulose from hemp and cotton
Dextrin	It is a food additive Е1400. Also used in the manufacture of adhesives	Prepared from starch by heat treatment
Agar-agar	This substance and its derivatives are used as stabilizers in the manufacture of food (for example, ice cream and marmalade), varnishes, paints	Obtain from brown algae, since it is one of the components of their cell membrane

Now you know what polysaccharides are, what they are used for, what their role in the body is, what physical and chemical properties they have.