Polysaccharides

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What are polysaccharides?

Polysaccharides are carbohydrates that contain more than 2 monosaccharides (glucose, fructose, and galactose). These types of carbohydrates can be linear or branched in structure.

Some examples of polysaccharides include cellulose, chitin, glycogen, starch, and hyaluronic acid.

The main functions of polysaccharides include structural support, energy storage, and cellular communication. The carbohydrate structure largely determines its function. Linear molecules, like cellulose and chitin, are strong and rigid. Cellulose is the primary support molecule in plants, while fungi and insects rely on chitin.

Functions of polysaccharides

Structural support

A polysaccharide can be combined with a variety of other ingredients to produce more rigid or less rigid tissues, as well as materials with specific properties. Polysaccharides can be present in anything from tree wood to sea creature shells.

Polysaccharides can transform from storage molecules to much stronger fibrous molecules simply by rearranging their structure. Most monosaccharides’ ring structure aids this process.

Energy storage

Energy-storing polysaccharides are typically branched and folded on themselves. They are normally insoluble in water due to their high hydrogen bonding content. Starch in plants and glycogen in animals are examples of storage polysaccharides.

Though energy-producing enzymes only operate on the monosaccharides contained in a polysaccharide, polysaccharides fold together and may contain a large number of monosaccharides in a small space. Furthermore, since the monosaccharide side chains form as many hydrogen bonds as possible with each other, water cannot penetrate the molecules, rendering them hydrophobic. This keeps the molecules together and prevents them from dissolving in the cytosol. This decreases the sugar content in a cell, allowing more sugar to be absorbed providing energy.

Cellular communication

Signals can be sent between and inside cells using glycolipids and glycoproteins. The carbohydrate serves as a tag to help the signal reach the proper target. Categories of glycoconjugates include glycoproteins, peptidoglycans, glycosides, and glycolipids.

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