17 Electron micrograph of the cellulose fibers in the cell wall of the alga, Chaetomorpha melagonium
18 Primary structure of cellulose: Primary structure of cellulose: b-D-glucopyranosyl-(1,4)-b-D-glucopyranosyl
19 Proposed structural model of cellulose ExtensiveH-bondingnetwork (intra-and interchain:responsible forthe rigidity ofcellulose fibersProposed structural model of cellulose
20 Primary structure of chitin: ......b-D-GlcNAc-(1,4)-b-D-GlcNAc-...... A structural motif similar to that of cellulose:thus, similar physical properties (structure-function correlations)
21 a-Amylose: D-glucose residues are linked by a-(1 ® 4) bonds (red) ......a-D-glucopyranosyl-(1,4)-a-D-glucopyranosyl
22 a-Amylose: this regularly repeating polymer forms a left-handed helix.
23 Amylopectin: Primary structure near one of it’s a-(1® 6) branch points (red)
24 Glycogen is amylopectin-like but with greater branching Amylopectin showing its bushlike (compact, globular) structure (glucose residues at branch points indicated in red)Glycogen is amylopectin-like but with greater branching
25 Photomicrograph showing the glycogen granules (pink) in the cytoplasm of a liver cell
26 N-Linked oligosaccharides: all N-glycosidic protein attachments occur through a N-acetyl-b-D-glucosamine–Asn bond to Asn–X–Ser/Thr
27 N-Linked oligosaccharides: N-linked oligosaccharides usually have the branched (mannose)3(NAG)2 core shown
28 N-Linked oligosaccharides: some examples of N-linked oligosaccharides
29 The microheterogeneous N-linked oligosaccharide of RNase B has the (mannose)5(NAG)2 core shown
30 Some common O-glycosidic attachments of oligosaccharides to glycoproteins (red): blood group antigens (glycophorin)
31 Disaccharide repeating units of the common glycosaminoglycans (proteoglycans): connective tissue; cartilage
32 X-ray fiber structure of Ca2+ hyaluronate Hyaluronidase:a glycosidase thatcleaves the b-(1,4)linkages ofhyaluronic acidX-ray fiber structure of Ca2+ hyaluronate
33 Proteoglycans: (a) Electron micrograph showing a central strand of hyaluronic acid. (b) Bottlebrush model of the proteoglycan aggrecan.
34 Model of oligosaccharide dynamics in bovine pancreatic ribonuclease B (RNase B)
35 Schematic diagram comparing the cell envelopes of (a) gram-positive bacteria and (b) gram-negative bacteria
36 Chemical structure of peptidoglycan of bacteria: the repeating unit of peptidoglycan
37 cross-linkages between the chains Note the pentaglycinecross-linkages betweenthe chainsLysozyme: a glycosidasethat cleaves the b-(1,4)linkages of peptidoglycansChemical structure of peptidoglycan: the S. aureus bacterial cell wall peptidoglycan
38 Structure of penicillin: inhibits bacterial cell wall biosynthesis
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