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2.6.1. Homopolysaccharides

Homopolysaccharides

The Homopolysaccharides are classified according to the type of monosaccharide that is repeated and the type of link.

Its function depends on the type of O-glucosidic bond.

  • In the case of α bonds, the polysaccharide acts as an energy reserve, since it can easily hydrolyze and separate the monosaccharides. As polysaccharides are not soluble in water, they constitute the ideal form of accumulation of carbohydrates, since osmotic problems are avoided in the cells in which they are found.
  • In contrast, β- linked polysaccharides are very difficult to hydrolyze (corresponding enzymes are rare) and therefore perform structural functions.

Fundamental ideas about homopolysaccharides

The  polysaccharides  are  biomolecules formed by the union of many monosaccharides (even thousands) through  O-glycosidic bonds, shedding a water molecule per link.

Its function depends on the type of  O-glucosidic bond.

  • Link α-glycosidicPolysaccharides with this type of bond have an energy reserve function, are easily hydrolyzable and monosaccharides are separated.
    • Glycogen: Homopolysaccharide energy reserve of animals.
    • Starch:  Homopolysaccharide energy reserve of vegetables.
  • Link  β-glycoside Polysaccharides with this type of bond have a structural function, they are difficult to hydrolyze, so it is not easy to separate the monosaccharides that compose them. Many organisms cannot digest them because they lack the necessary enzymes to do so.
    • CelluloseHomopolysaccharide with structural function in vegetables.
    • Chitin:  Homopolysaccharide with structural function in the exoskeleton of  arthropods (insects,  crustaceans, etc.). It is also part of the cell coatings of fungi.