1. Carbohydrates and Glycobiology

2. Representative Monosaccharides

3. Most of the hexoses of living organisms are D isomers

4. Mannose and Galactose are epimers of Glucose

5. Structures of the D-Aldoses

6. Structures of the D-Ketoses

7. Formation of Hemiacetals and Hemiketals
Aldotetroses and all monosaccharides with five or more carbon atoms occur predominantly as cyclic ring structures in which the carbonyl group has formed a covalent bond with the oxygen of a hydroxyl group along the chain. The formation of these ring structures is the result of a general reaction between alcohols and aldehydes or ketones to form derivatives called hemiacetals or hemiketals (Fig. 7-5). Actually, two molecules of an alcohol can add to a carbonyl carbon. The product of the first reaction for an aldose is a hemiacetal, and the product of the first reaction for a ketose is a hemiketal. If the -OH and carbonyl groups are from the same molecule, a five- or six-membered ring results. The addition of the second alcohol molecule produces the full acetal or ketal, and the bond formed is a glycosidic linkage. When the two reacting molecules are both monosaccharides, the acetal or ketal produced is a disaccharide.

8. Formation of the two cyclic forms of D-glucose
In aqueous solution monosaccharides with five or more carbons occur as cyclic structures.
Two stereoisomers are produced and called alpha (a) and beta (b).

12. Disaccharides contain a glycosidic bond

13. Common Disaccharides

15. Starch Structure
Amylopectin and Glycogen

16. Cellulose

17. French Fries versus Fiber
Humans digest starch and glycogen ingested in their
diet using α-amylases, enzymes that hydrolyze
(α 14) glycosidic bonds.
Humans cannot hydrolyze (β14) linkages of
cellulose. Therefore cellulose is not a fuel source
for humans. It is fiber.
Certain microorganisms have cellulases, enzymes that
hydrolyze (β 14) linkages of cellulose.
Cattle have these organisms in their rumen.
Termites have them in their intestinal tract.

18. Chitin is the principal component of the exoskeleton of arthropods like insects, lobsters, and crabs
Linear homopolysaccharide of N-acetylglucosamine in β(14) linkage

19. Agarose is a heteropolysaccharide found in the cell walls of some seaweed

21. Cellular location of carbohydrates

22. Proteoglycan aggregate of the extracellular matrix

23. Lipopolysaccharide of the outer membrane of the bacterium Salmonella typhimurium

24. Role of lectin-ligand interaction in leukocyte movement to the site of an infection or injury