Polysaccharides and Glycoproteins PDF
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This document provides a comprehensive overview of polysaccharides, including their structures, functions, and examples like starch, glycogen, and cellulose. It also discusses how carbohydrates are involved in cell surface interactions and immune responses. The information is presented visually with diagrams.
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Polysaccharides Monosaccharides, Disaccharides (2 x mono), Trisaccharides (3 x mono) Oligosaccharides (4 – 20 x mono) Starch Polysaccharides (>20 x mono) Glycogen Cellulose Starch Polymer that serves as a...
Polysaccharides Monosaccharides, Disaccharides (2 x mono), Trisaccharides (3 x mono) Oligosaccharides (4 – 20 x mono) Starch Polysaccharides (>20 x mono) Glycogen Cellulose Starch Polymer that serves as a glucose-storage in plants Forms insoluble granules in storage organelles (plastids) Consists of unbranched and branched polymers of α-D-glucose monomers Amylose Unbranched polymer in starch = amylose Only 1,4 glycosidic bonds Helical shape due to H-bonds between glucose monomers Amylopectin Branched polymer in starch = amylopectin Branches formed by 1,6 glycosidic bonds between some glucose monomers Starch Branching structure results in many free ends Polymer ends enables rapid addition (storing surplus glucose) and removal of glucose (mobilizing glucose for energy) Glycogen Polymer that serves as a glucose-storage in animals Glycogen stored in liver and muscle cells in mammals Extensively branched polymer of α-D-glucose monomers Glycogen Structure similar to amylopectin – larger and with many more branches! Many free ends allow for more rapid hydrolysis of glycogen to release glucose when energy is quickly needed (adaptation to movement) Cellulose Cellulose is the basic component of plant cell walls Straight, unbranched polymer of β-D-glucose (1,4 glycosidic bonds) Orientation of glucose monomers alternates Cellulose Parallel chains of cellulose cross-linked with hydrogen bonds = microfibrils Meshwork of many microfibrils results in a very strong and slightly flexible material Polysaccharides - summary Carbohydrates on cell surfaces Many cell types have a sugar-coated cell membrane exterior Shorter polysaccharides are attached to membrane proteins (glycoproteins) and lipids (glycolipids) Carbohydrates on cell surfaces Glycoproteins allow for cell recognition, communication and adhesion Important for the immune system to recognize ”self-cells” from foreign cells (eg pathogens that should be attacked) Presence of different glycoproteins defines the ABO blood types (red blood cells)
