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Oligosaccarides and Polysaccharides

Oligosaccarides and Polysaccharides . Complex Carbohydrates. Lactose, a disaccharide. a reducing sugar; exhibits mutarotation 1,4-acetal linkage between 2 monomeric sugars acidic hydrolysis yields galactose and glucose (1:1). Maltose, a disaccharide. a reducing sugar; mutarotates

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Oligosaccarides and Polysaccharides

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  1. Oligosaccarides and Polysaccharides Complex Carbohydrates

  2. Lactose, a disaccharide • a reducing sugar; exhibits mutarotation • 1,4-acetal linkage between 2 monomeric sugars • acidic hydrolysis yields galactose and glucose (1:1).

  3. Maltose, a disaccharide • a reducing sugar; mutarotates • acidic hydrolysis yields only glucose • can be digested by humans & fermented by yeast.

  4. Cellobiose, a disaccharide • a reducing sugar; mutarotates • can NOT be digested by humans nor fermented by yeast; CAN be digested by bacteria in ruminants and termites (which have -glucosidase enzyme).

  5. Sucrose, a disaccharide • NOT a reducing sugar; NOT a hemiacetal; does NOT undergo mutarotation • hydrolysis yields glucose plus fructose (called “invert sugar” because rotation of polarized light changes sign).

  6. Cellulose, a polysaccharide • acid hydrolysis yields only glucose • can have thousands of monomers linked; only one anomeric carbon; mutarotation occurs, NOT observed • rigid structure; hydrolyzed by -glucosidase enzymes.

  7. Starch: a mixture of linear and branched polysaccharides • energy storage for plants (potatoes) • hydrolyzed readily by humans; yields only glucose.

  8. Starch: the branched component • a much larger and more highly branched polysaccharide (GLYCOGEN) provides energy storage in animals.

  9. Ethanol production • Ethanol can be produced by fermentation of simple sugars promoted by yeast. • Corn and other grains are major sources of simple sugars, but much more carbohydrate-containing biomass is in the form of polysaccharides such as cellulose.

  10. Ethanol production • Efforts are now underway to utilize the otherwise wasted (as a fuel source) polysaccharides by hydrolyzing them to their component monosaccharides followed by fermentation. • Other plant sources of both simple and complex carbohydrates are being investigated as possible sources of ethanol for fuel. • These include switchgrass, sugar cane, and even kudzu.

  11. Other important carbohydrates

  12. Cell-Surface Carbohydrates: Blood Typing • The surface of human blood cells has proteins covalently bound via glycoside bonds to oligosaccharides that serve as antigens. • For a human to accept blood from a donor, their blood types must be compatible; otherwise, agglutination (clotting) occurs. • Compatibility depends on the identity of the sugars in the oligosaccharides bound to the surface proteins.

  13. Type A Blood

  14. Type B Blood

  15. Type O Blood Recent research has led to isolation of a bacterial enzyme that cleaves the sugar bonded to the 3-position of galactose in type A and B peptides to make O-type

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