Carbohydrates -IV-

Polysaccharides

3 Polysaccharides Polysaccharides are polymers of 10 or more monosaccharide units Homopolysaccharides: Homopolysaccharides: Contain a single type of monosaccharide units. Contain a single type of monosaccharide units. Heteropolysaccharides: Heteropolysaccharides: Contain more than one type of monosaccharide units. Contain more than one type of monosaccharide units.

Polysaccharides Polysaccharides Include amylose and amylopectin, starches made of α-D-glucose.Include amylose and amylopectin, starches made of α-D-glucose. Include glycogen (animal starch in muscle), which is made of α-D-glucose.Include glycogen (animal starch in muscle), which is made of α-D-glucose. Include cellulose (plants and wood), which is made of β-D-glucose.Include cellulose (plants and wood), which is made of β-D-glucose. α-D-glucose

5 Structures of Amylose and Amylopectin

Amylose Amylose is A polymer of α-D-glucose molecules.A polymer of α-D-glucose molecules. Linked by  -1,4 glycosidic bonds.Linked by  -1,4 glycosidic bonds. A continuous (unbranched) chain.A continuous (unbranched) chain. Produced by plants for glucose storage.Produced by plants for glucose storage.

Amylopectin Amylopectin Is a polymer of α-D-glucose molecules.Is a polymer of α-D-glucose molecules. Is a branched-chain polysaccharide.Is a branched-chain polysaccharide. Has α-1,4-glycosidic bonds between the glucose units.Has α-1,4-glycosidic bonds between the glucose units. Has α-1,6 bonds to branches.Has α-1,6 bonds to branches. -

Glycogen Glycogen Is the polysaccharide that stores α-D-glucose in muscles and liver.Is the polysaccharide that stores α-D-glucose in muscles and liver. Is similar to amylopectin, but is more highly branched.Is similar to amylopectin, but is more highly branched.

Cellulose Cellulose Is a structural polymer produced by plants.Is a structural polymer produced by plants. Is a polysaccharide of glucose units in unbranched chains.Is a polysaccharide of glucose units in unbranched chains. Has β-1,4-glycosidic bonds.Has β-1,4-glycosidic bonds. Cannot be digested by humans because humans cannot break down β-1,4-glycosidic bonds.Cannot be digested by humans because humans cannot break down β-1,4-glycosidic bonds.

Polysaccharides Cellulose forms a very insoluble, fibrous network Cellulose forms a very insoluble, fibrous network Cannot be digested by humans and Most organisms, because they lack the enzymes needed to break the β(1→4) glycosidic bonds Cannot be digested by humans and Most organisms, because they lack the enzymes needed to break the β(1→4) glycosidic bonds

Chitin Exoskeletons of insects, spiders, and cell walls of fungi.Exoskeletons of insects, spiders, and cell walls of fungi. Similar to cellulose, but instead of glucose uses N- acetyl glucosamine (C-2s are N-acetyl instead of – OH).Similar to cellulose, but instead of glucose uses N- acetyl glucosamine (C-2s are N-acetyl instead of – OH). β-1,4 linked N-acetylglucosamine units.β-1,4 linked N-acetylglucosamine units.

Chitin

Oligosaccharides There are also oligosaccharides with 3 or more monosaccharides The blood group antigens are oligosaccharides that are attached to lipids and proteins found on cell surfaces. The blood group antigens are oligosaccharides that are attached to lipids and proteins found on cell surfaces.

The End