J1_monosaccharides_and_disaccharides

1、J1 Monosaccharides and disaccharidesmonosaccharide 单糖单糖 disaccharide 双糖双糖aldose 醛糖醛糖 ketose 酮糖酮糖 pentose 戊糖戊糖 hexose 己糖己糖glucose 葡萄糖葡萄糖 galactose 半乳糖半乳糖 mannose 甘露糖甘露糖 fructose 果糖果糖reducing sugar 还原糖还原糖 glycosidic bond 糖苷键糖苷键 epimer 差向异构体差向异构体 sugar derivative糖衍生物糖衍生物structure isomer 结构异构体结构异构体 ster

2、eoisomer 立体异构体立体异构体 1 Aldoses(醛糖醛糖) and ketoses(酮糖酮糖) A carbohydrate is composed of carbon (carbo-), and hydrogen and oxygen (-hydrate). The simplest carbohydrates are the monosaccharide or simple sugar. There are two types of monsaccharide:(1)aldose: bears an aldehyde group （醛基（醛基, CHO）(2) ketose:

3、bears a ketone group （酮基（酮基, CO）The smallest carbohydrate is triose （丙糖）（丙糖）.Having same chemical composition, but differ in structurestructure isomers (结构异构体结构异构体)Sugars that contain a free aldehyde or ketone group in the open-chain configuration can reduce cupric ions (Cu2+) to cuprous ions (Cu+)

4、and are called reducing sugars.葡萄糖酸葡萄糖酸2 Stereoisomers (立体异构体立体异构体) Glyceraldehyde（甘油醛）（甘油醛） has a single asymmetric carbon atom and two stereoisomers are possible, that is two forms of glyceraldehydes, D-and L-glyceraldehyde.投影式投影式asymmetric carbon atom 不对称碳原子不对称碳原子透视表示式透视表示式 triose tetrosePentose

5、戊糖戊糖核糖核糖Hexose 己糖己糖 葡萄糖葡萄糖 甘露糖甘露糖 半乳糖半乳糖二羟丙糖二羟丙糖果糖果糖D sugars that differ in configuration （构型）（构型）at only a single asymmetric carbon atom are called epimers（差向异构体）（差向异构体）. 2 Ring structuresThe aldehyde or ketone group can react with a hydroxyl group to form a covalent bond. 半缩醛半缩醛半缩酮半缩酮For tetroses

6、and larger sugars, the reaction can take place within the same molecule so that the straight-chain form of the sugar cyclizes. A new asymmetric center is formed during cyclization, at C-1. Two isomers （ and ）exist. 葡萄吡喃糖葡萄吡喃糖吡喃吡喃呋喃呋喃 All the axial positions are occupied by hydrogen atoms. 3 Disaccha

7、rides The aldehyde or ketone group on the anomeric carbon atom (异头碳原子异头碳原子)of one monosaccharide can react with the hydroxyl group of a second monosaccharide to form a disaccharide. glycosidic bond 糖苷键糖苷键麦芽糖麦芽糖reducing end 还原端还原端乳糖乳糖蔗糖蔗糖4 Sugar derivatives (糖衍生物糖衍生物) The hydroxyl groups of simple monosaccharides can be replaced with other groups to f