16 16 1 16 Polysaccharides Cellulose the major

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16 Polysaccharides • Cellulose: the major structural component of plants, especially wood and plant fibers • a linear polymer of approximately 2800 D-glucose units per molecule joined by -1, 4 -glycosidic bonds • fully extended conformation with alternating 180° flips of glucose units • extensive intra- and intermolecular hydrogen bonding between chains 16 -2

� Cellulose is important source of energy for animals � And it is very important for our digestive system. � It contains glucose but different in linkage beta (1 -4)

� Cellulose also decrease absorption of lipids (fat) and cholesterol , so it decrease cancer risk , because cancer increase by increasing fat and consumption of protein � decrease cholesterol , decrease artery thersosis , decrease cardiovascular disease , weight decrease � Cellulose is digestive by animals because they have cellulase enzyme in bacteria which located in their digestive system

Carbohydrates – Complex (Polysaccharides) 16 Cellulose fibers Cellulose = polysaccharide found in plant cell walls Macrofibril Microfibril Chains of cellulose 16 -5

16 Starch • A polymers of -D-glucose units and used for energy storage in plants, 2 forms • amylose: continuous, helical unbranched chains of up amylose to 4000 -D-glucose units joined by -1, 4 -glycosidic bonds • amylopectin: a highly branched helical polymer amylopectin consisting of 24 -30 units of D-glucose joined by _1, 4 -glycosidic bonds and branches created by -1, 6 -glycosidic bonds • amylases catalyze hydrolysis of -1, 4 -glycosidic bonds • debranching enzymes catalyze the hydrolysis of -1, 6 -glycosidic bonds 16 -6

� Amylase found in saliva � And there are two type: � Salivary amylase and pancreatic amylase. � both are the same but pancreatic amylase continue to digest what salivary amylase that begin to digest it.

16 Starch 16 -8

16 Polysaccharides Branching in amylopectin and glycogen 16 -9

Glycogen is the energy storage of glucose in animals , and we find it in muscles and liver. � It is highly branched and globular. It is highly branched to decrease the storage space , and it is easy to dissociated and to synthesis. Our body use the storage of glycogen when we do exercise ( in muscles ) or fasting (in liver). In case of hypocalcemia? When blood sugar level decrease the glycogen will give blood to body to rest of body. *Blood glucose necessary for brain �

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� Cellulose, Cellulose chitin and starch are all called homopolysaccharides

16 Polysaccharides • Chitin: the major structural component of the Chitin: exoskeletons of invertebrates, such as insects and crustaceans; also occurs in cell walls of algae, fungi, and yeasts • composed of units of N-acetyl- -D-glucosamine joined by -1, 4 -glycosidic bonds 16 -15

16 Polysaccharides • Bacterial cell walls: prokaryotic cell walls are Bacterial cell walls: constructed on the framework of the repeating unit NAM-NAG joined by -1, 4 -glycosidic bonds 16 -16

16 Bacterial Cell Walls • The N-acetyl-D-glucoseamine and N-acetylmuramic acid polysaccharide is in turn cross-linked by small peptides • in Staphylococcus aureus, the cross link is a tetrapeptide • this tetrapeptide is unusual in that it contains two amino acids of the D-series, namely D-Ala and D-Gln • each tetrapeptide is cross linked to an adjacent tetrapeptide by a pentapeptide of five glycine units • Peptidoglycan: is the resulted cross linking of polysaccharides by peptides 16 -17

16 Bacterial Cell Walls 16 -18

16 Bacterial Cell Walls The peptidoglycan of a bacterial cell wall Staphylococcus aureus 16 -19

16 End 16 -20