Polysaccharides and Starch Quiz

Polysaccharides

• Polysaccharides are high molecular weight carbohydrates
• They are insoluble non-sugars
• On hydrolysis, they yield monosaccharides or related products
• They're polymeric anhydrides of simple sugars
• D-glucose is a key component

Polysaccharide Types

• Homopolysaccharides: Yield a single monosaccharide on hydrolysis
  • Storage: Starch, glycogen, inulin
  • Structural: Cellulose, pectin, chitin
• Heteropolysaccharides: Yield a mixture of monosaccharides on hydrolysis
  • Glycosaminoglycans (mucopolysaccharides): Hyaluronic acid, chondroitin sulfates (A and C), dermatan sulfate, and keratosulfate, heparin
• Other constituents: D- and L-galactose, D-mannose, D-xylose, L-arabinose, D-glucuronic acid, D-galacturonic acid, D-mannuronic acids, D-glucoseamine, D-galactoseamine, aminouronic acids

Polysaccharide Functions

• Energy storage: Starch, glycogen, inulin
• Structural components: Cellulose, pectin, chitin, glycosaminoglycans
• Other functions: Aids in digestion, make up cell and tissue structures, and are a source of carbon for synthesis of other compounds

Starch

• Polymer of α-glucose
• Stored as starch grains in chloroplasts and storage organs (e.g., potatoes, seeds)
• Consists of two types:
  • Amylose (linear, helical)
  • Amylopectin (branched)
• More than half of human carbohydrate intake is starch

Glycogen

• D-Glucose linked by α-1,4 and α-1,6 glycosidic bonds
• Branches formed after 8-10 residues
• A major energy reserve in animals
• Stored in the liver and muscles (up to 7% of wet weight)
• Particles much smaller than starch grains

Inulin

• Polymer of D-fructose, β-(1,2) linked fructofuranoses
• Linear, no branching
• Lower molecular weight than starch
• Colors yellow with iodine
• Hydrolysis yields fructose
• Stored in tubers (dahlia, artichoke) and roots (dandelion)
• Used as a dietary fiber, appetite suppressant, and in treating kidney disease

Cellulose

• Linear polymer of β-D-glucose linked by β(1−4) glycosidic bonds
• Most abundant polysaccharide
• Present in all land plants, but not in animals
• Not digestible by humans
• Forms plant cell walls (40-70%)

Pectin

• Polysaccharide of α-D-galacturonic acid
• Found as intercellular substances in young plants and fruits
• Forms jellies with sugars
• Used as gelling agent in jams and jellies

Chitin

• Polymer of N-acetyl-D-glucosamine, β(1→4) glycosidic bonds.
• Important structural component in fungi, crab shells, and insect exoskeletons.
• Impregnated with calcium carbonate to enhance strength

Heteropolysaccharides (Glycosaminoglycans)

• Polymers assembled from disaccharides
• Mucopolysaccharide disorders are caused by defective lysosomal enzymes
• Examples: hyaluronic acid, chondroitin sulfates (A and C), dermatan sulfate and keratosulfate, and heparin

Hyaluronic Acid

• Straight-chain polymer of D-glucuronic acid and N-acetyl-D-glucosamine (NAG)
• Abundant in connective tissues (synovial fluid, vitreous humor of eye)
• High viscosity, acts as a lubricant and helps cement tissues
• Involved in fertilization

Chondroitin

• Related to hyaluronic acid
• Polymer of D-glucuronic and N-acetyl-galactosamine
• Component of cartilage, tendons and cell coats

Chondroitin Sulfates (A and C)

• Modifications of chondroitin with sulfate
• Widely distributed in cartilage, tendons, and bones
• Contribute to structural support

Dermatan Sulfate

• Structurally similar to chondroitin sulfate A
• Contains L-iduronic acid instead of D-glucuronic acid
• Component of connective tissues

Heparin

• Sulfated heteropolysaccharide
• Anticoagulant, inhibits blood clotting
• Found in liver, lungs, and mast cells

Proteoglycans

• Core proteins covalently attached to glycosaminoglycans
• Important components of connective tissues

Uses of Polysaccharides

• Water treatment: remove metal ions, filtration
• Pulp and paper: surface treatment
• Biomedical: bandages, sponges, artificial materials, controlling drug release
• Cosmetics: make-up powder nail polish, moisturizers
• Biotechnology: enzyme/cell immobilization, protein separation
• Agriculture: seed/leaf coating, fertilizer

Test your knowledge about polysaccharides and starch in this informative quiz. Explore questions regarding their functions, types, and properties. Perfect for students studying biochemistry or related fields.