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σακχαρων Greek “ sakcharon” = sugar

σακχαρων Greek “ sakcharon” = sugar. Carbohydrates – polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH 2 O) n , or compounds that can be hydrolyzed to them. (aka sugars or saccharides)

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σακχαρων Greek “ sakcharon” = sugar

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  1. σακχαρων Greek “sakcharon” = sugar

  2. Carbohydrates – polyhydroxyaldehydes or polyhydroxy-ketones of formula (CH2O)n, or compounds that can be hydrolyzed to them. (aka sugars or saccharides) Monosaccharides – carbohydrates that cannot be hydrolyzed to simpler carbohydrates; eg. Glucose or fructose. Disaccharides – carbohydrates that can be hydrolyzed into two monosaccharide units; eg. Sucrose, which is hydrolyzed into glucose and fructose. Oligosaccharides – carbohydrates that can be hydrolyzed into a few monosaccharide units. Polysaccharides – carbohydrates that are are polymeric sugars; eg Starch or cellulose.

  3. Aldose – polyhydroxyaldehyde, eg glucose Ketose – polyhydroxyketone, eg fructose Triose, tetrose, pentose, hexose, etc. – carbohydrates that contain three, four, five, six, etc. carbons per molecule (usually five or six); eg. Aldohexose, ketopentose, etc.

  4. Reducing sugar – a carbohydrate that is oxidized by Tollen’s, Fehling’s or Benedict’s solution. Tollen’s: Ag+ Ag (silver mirror) Fehling’s or Benedict’s: Cu3+ (blue)  Cu2+ (red ppt) These are reactions of aldehydes and alpha-hydroxyketones. Allmonosaccharides (both aldoses and ketoses) and most* disaccharides are reducing sugars. *Sucrose (table sugar), a disaccharide, is not a reducing sugar.

  5. Glucose (a monosaccharide) Plants: photosynthesis chlorophyll 6 CO2 + 6 H2O C6H12O6 + 6 O2 sunlight (+)-glucose (+)-glucose starch or cellulose respiration C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

  6. Animals plant starch (+)-glucose (+)-glucose glycogen glycogen (+)-glucose (+)-glucose fats or aminoacids respiration (+)-glucose + 6 O2 6 CO2 + 6 H2O + energy

  7. (+)-glucose? An aldohexose Emil Fischer (1902) Four chiral centers, 24 = 16 stereoisomers

  8. Ruff degradation – a series of reactions that removes the reducing carbon ( C=O ) from a sugar and decreases the number of chiral centers by one; used to relate configuration.

  9. Kiliani-Fischer synthesis. A series of reactions that extends the carbon chain in a carbohydrate by one carbon and one chiral center.

  10. Epimers – stereoisomers that differ only in configuration about one chiral center.

  11. Exists only in solution. There are two solids: α-glucose m 146o [α] = +112.2 β-glucose m 150o [α] = +17.5 In water each mutarotates to an equilibrium with [α] = +52.7 (63.6% β / 36.4% α)

  12. Addition of alcohols to aldehydes/ketones:

  13. Disaccharides: (+)-maltose “malt sugar” two glucose units (alpha) (+)-cellobiose two glucose units (beta) (+)-lactose “milk sugar” galactose & glucose (+)-sucrose “table sugar” glucose & fructose

  14. Polysaccharides starch cellulose Starch 20% amylose (water soluble) 80% amylopectin (water insoluble) amylose + H2O  (+)-maltose (+)-maltose + H2O  (+)-glucose starch is a poly glucose (alpha-glucoside to C-4)

  15. Amylopectin + H2O  (+)-maltose (+)-maltose + H2O  (+)-glucose Also a polyglucose, but branched every 20-25 units:

  16. Cellulose is a polyglucose with a beta-linkage:

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