文档介绍：Chapter 12 Sugar, Carbohydrates, and Glycobiology(糖生物学)
1. Carbohydrates are aldehyde or pounds with multiple hydroxyl groups or substances that can yield pounds on hydrolysis (p. 293)
Carbohydrates are the most abundant biomolecules on earth and have multiple roles in all forms of life.
Carbohydrates serve as energy stores (., starch in plants, glycogen in animals), fuels (., glucose), and metabolic intermediates (., ATP, many coenzymes).
Carbohydrates serve as structural elements in cell walls of plants (cellulose) or bacteria (peptidoglycans), exoskeletons of arthropods (chitin), and extracellular matrixes of vertebrate animals (proteoglycans).
Carbohydrates serve as recogntion signals in glycoproteins and glycolipids determining cell-cell recognition, intracellular location, and metabolic fates of proteins (thus sugars, like nucleic acids and proteins, are also information rich! But codes unknown).
Carbohydrates (ribose and deoxyribose) form part of the structural framework of RNA and DNA.
Carbohydrates can be categorized into harides, harides, and hrides.
hrides are simple sugars consisting of a single polyhydroxyl aldehyde or ketone unit (., glyceraldehyde, dihydroxyacetone, ribose, glucose, galatose, ribulose, and fructose).
harides contain two (harides) or a few harides joined by glycosidic bonds (., lactose, sucrose, maltose, some covalently linked sugars in glycoproteins and glycolipids).
harides contain long chains of (hundreds to thousands) haride units joined by glycosidic bonds (., glycogen, starch, cellulose, chitin, and glycosaminoglycans).
2. hrides contain one carbonyl group and two or more hydroxyl groups. (p. 294)
hrides can be divided into two families: aldoses and ketoses.
Aldoses have their carbonyl groups at the ends of the carbon chains, thus being an aldehyde.
Ketoses have their carbonyl groups at places other than the ends,, thus being ketones