Chapter 13 - Carbohydrate

13.1 - Carbohydrates

  • Carbs are classified as single sugars, disaccharides, or polysaccharides carbohydrates.   * Monosaccharides are aldehydes or ketones of polyhydroxy.
  • In their count of carbonic atoms monosaccharides are also classified: triosis, tetrosis, pentose, or hexoses.

13.2 - Chiral Molecules

  • Chiral molecules are mirror-imaged molecules that do not overlap.   * These stereoisomer types are referred to as enantiomers.
  • At least one chiral carbon must be a chiral molecule that is a carbon bonded to 4 different atoms or groups of atoms.
  • The Fischer project is a simplified way of arranging atoms, placed at a crossroads between vertical and horizontal lines by placing carbon atoms.

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13.3 - Fischer Projections of Monosaccharides

  • The − OH group is to the right of the chiral carbon away from the carbonyl group in a d enantiomer; the − OH group is to the left in the l enantiomer
  • Aldohexoses, glucose and galactose as well as ketohexose, fructose are important monosaccharides.

13.4 - Haworth Structures of Monosaccharides

  • A ring of five or six atoms is the predominant form of a monosaccharide.   * The cyclic structure forms if a − − OH group reacts with the same molecule carbonyl group (normally one on carbon-5 hexoses).
  • Cyclic monosaccharide isomers are produced by the formation of a new hydroxy group for carbon 1.

13.5 - Chemical Properties of Monosaccharides

  • In an aldose, the aldehyde group is oxidized into a carboxylic acid, while in an aldose or ketosis the carbonyl group can be reduced to the hydroxyl group.
  • The monosaccharides which reduce sugars have an open-chain aldehyde group that is oxidizable.

13.6 - Disaccharides

  • Disaccharides are two units combined by a glycosidic bond.   * There is at least one glucose unit in the common disaccharides maltose, lactose, and sucrose
  • Maltose and lactose form an isomer and b, which reduces sugar.   * Sucrose has no isomers and is not sugar reduction

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13.7 - Polysaccharides

  • Polysaccharides are monosaccharide polymers
  • Glycogen is more branched, like amylopectin   * Cellulose is also a glucose polymer, but b(1S4) bonds are the glycoside bond in cellulose.

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