Polysaccharides

(noun)

Polysaccharides are long, carbohydrate molecules of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit.

Related Terms

Examples of Polysaccharides in the following topics:

  • Polysaccharide Biosynthesis

    • Polysaccharides are synthesized from two forms of activated glucose molecules: UDP-glucose and ADP-glucose.
    • Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit.
    • One of the most common building block of polysaccharides is glucose.
    • Pathogenic bacteria commonly produce a thick, mucous-like, layer of polysaccharide.
    • Describe the mechanism of polysaccharide biosynthesis and its importance in bacteria

  • Glycocalyx

    • A glycocalyx(capsule or slime layer)is an external coating of bacteria with protective function, made mostly of polysaccharides.
    • A glycocalyx, literally meaning "sugar coat", is a network of polysaccharides that project from cellular surfaces of bacteria, which classifies it as a universal surface component of a bacterial cell, found just outside the bacterium cell wall.
    • It usually consists of polysaccharides, but can be composed of other materials (e.g., polypeptide in B. anthracis).

  • ABC Transporters

    • In gram-negative bacteria, exporters transport lipids and some polysaccharides from the cytoplasm to the periplasm.
    • In bacterial efflux systems, certain substances that need to be extruded from the cell include surface components of the bacterial cell (e.g. capsular polysaccharides, lipopolysaccharides, and teichoic acid), proteins involved in bacterial pathogenesis (e.g. hemolysis, heme-binding protein, and alkaline protease), heme, hydrolytic enzymes, S-layer proteins, competence factors, toxins, antibiotics, bacteriocins, peptide antibiotics, drugs and siderophores.
    • They also play important roles in biosynthetic pathways, including extracellular polysaccharide biosynthesis and cytochrome biogenesis.

  • Biosynthesis and Energy

    • An additional biosynthetic pathway utilized by microorganisms includes the synthesis of sugars and polysaccharides.
    • The ability to synthesize sugars and polysaccharides from noncarbohydrate precursors is key to survival in numerous microorganisms.

  • Nonthermophilic Crenarchaeota

    • The cells are cocci, 0.6-1.5 micrometres long, with sulfated polysaccharide walls.

  • Iron-Binding Proteins

    • Lactoferrin interacts with DNA and RNA, polysaccharides and heparin, and shows some of its biological functions in complexes with these ligands.

  • Cytophaga and Relatives

    • However, a few mechanisms have been partially identified in certain species that utilize the gliding locomotion and these include the use of a type IV pili, the use of focal adhesion complexes distributed through the body, and the use of a polysaccharide slime that is ejected from one the ends of the body.

  • Diverse Cell Forms of Methanogens

    • They are important for the efficient digestion of polysaccharides, allowing for an increase in the transformation of nutrients into calories.

  • Edible Algae

    • Some of the complex polysaccharides found in algae may be digested by bacteria in the gut since the needed enzymes for digestion are abundantly present in Japanese people but absent in people from North America.

  • Agglutination Reactions

    • Hemagglutination uses erythrocytes as the biological carriers of bacterial antigens, and purified polysaccharides or proteins for determining the presence of corresponding antibodies in a specimen .