Chapter 12 Sugar, Carbohydrates, and Glycobiology(糖生物学)
Chapter 12 Sugar, Carbohydrates, and Glycobiology（糖生物学）
1. Carbohydrates are aldehyde or ketone compounds with multiple hydroxyl groups or substances that can yield such compounds on hydrolysis(p. 293) 1.1 Carbohydrates are the most abundant biomolecules on earth and have multiple roles in all forms of life 1.1.1 Carbohydrates serve as energy stores (e.g., starch in plants, glycogen in animals), fuels(e.g, glucose, and metabolic intermediates(e.g, ATP, many coenzymes)
1. Carbohydrates are aldehyde or ketone compounds with multiple hydroxyl groups or substances that can yield such compounds on hydrolysis (p. 293) 1.1 Carbohydrates are the most abundant biomolecules on earth and have multiple roles in all forms of life. 1.1.1 Carbohydrates serve as energy stores (e.g., starch in plants, glycogen in animals), fuels (e.g., glucose), and metabolic intermediates (e.g., ATP, many coenzymes)
1.1.2 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)
1.1.2 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)
1.1.3 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) 1.1.4 Carbohydrates (ribose and deoxyribose) form part of the structural framework of rna and dna
1.1.3 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). 1.1.4 Carbohydrates (ribose and deoxyribose) form part of the structural framework of RNA and DNA
1.2 Carbohydrates can be categorized into monosaccharides. oligosaccharides and polysacchrides. 1.2.1 Monosacchrides are simple sugars consisting of a single polyhydroxyl aldehyde or ketone unit(e.g, glyceraldehyde, dihydroxyacetone, ribose, glucose, galatose, ribulose, and fructose)
1.2 Carbohydrates can be categorized into monosaccharides, oligosaccharides, and polysacchrides. 1.2.1 Monosacchrides are simple sugars consisting of a single polyhydroxyl aldehyde or ketone unit (e.g., glyceraldehyde, dihydroxyacetone, ribose, glucose, galatose, ribulose, and fructose)
1.2.2 Oligosaccharides contain two (disaccharides or a few monosaccharides joined by glycosidic bonds(e.g, lactose, sucrose, maltose,1d some covalently linked sugars in glycoproteins a glycoli Ias 1.2.3 Polysaccharides contain long chains of hundreds to thousands)monosaccharide units cellulose, chitin, and glycosangi glycogen, starch, joined by glycosidic bonds(e.g Iminoglycans)
1.2.2 Oligosaccharides contain two (disaccharides) or a few monosaccharides joined by glycosidic bonds (e.g., lactose, sucrose, maltose, some covalently linked sugars in glycoproteins and glycolipids). 1.2.3 Polysaccharides contain long chains of (hundreds to thousands) monosaccharide units joined by glycosidic bonds (e.g., glycogen, starch, cellulose, chitin, and glycosaminoglycans)
2. Monosacchrides contain one carbonyl group and two or more hydroxyl groups(p. 294) 2.1 Monosacchrides can be divided into two families: aldoses and ketoses 2. 1.1 Aldoses have their carbonyl groups at the ends of the carbon chains, thus being an aldehyde 2.1.2 Ketoses have their carbonyl groups at places other than the ends, thus being ketones. dehyde and the simplest ketose is dihyoxyacetone, both being triose
2. Monosacchrides contain one carbonyl group and two or more hydroxyl groups. (p. 294) 2.1 Monosacchrides can be divided into two families: aldoses and ketoses. 2.1.1 Aldoses have their carbonyl groups at the ends of the carbon chains, thus being an aldehyde. 2.1.2 Ketoses have their carbonyl groups at places other than the ends,, thus being ketones. 2.1.3 The simplest aldose is glyceraldehyde, and the simplest ketose is dihyoxyacetone, both being triose
2.1.4 Monosacchrides containing four, five, and six carbon atoms in their backbones are called tetroses, pentoses(e.g, ribose and deoxyribose), and hexoses(e.g, glucose and fructose), respectively. Each has both aldoses and ketoses 2.1.5 Hexoses are the most common monosacchrides in nature, including D-glucose, D-mannose, D-galactose, D-fructose
2.1.4 Monosacchrides containing four, five, and six carbon atoms in their backbones are called tetroses, pentoses (e.g., ribose and deoxyribose), and hexoses (e.g., glucose and fructose), respectively. Each has both aldoses and ketoses. 2.1.5 Hexoses are the most common monosacchrides in nature, including D-glucose, D-mannose, D-galactose, D-fructose
HO H H-C-OH H-C-OH C=0 H-C-OH H-C-OH H H Glyceraldehyde, Dihydroxyacetone an aldotriose a ketotriose
h O H C H-C-OH H-C-OH C=O HOC—H HO-C—H H-C-OH H-C-OH H-C-OH H-C-OH CHOH CHOH D-Glucose D-Fructose an aldohexose a ketohexose