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.

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

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.