1. Chapter 7
Chem 341
Suroviec Fall 2016

2. Carbohydrates
One of the 4 major classes of biomolecules
Make up most of the organic matter on Earth
Act as energy stores, fuels and metabolic intermediates
Ribose and deoxyribose sugars form framework of RNA and DNA
Polysaccharides make structural elements in cell walls
Carbohydrates are linked to many proteins and lipids
I. Monosaccarides (CH2O)n where n = 3-9
A. Naming
Are aldehyde or ketone derivatives of straight chain polyhydroxy alcohols containing at least 3 C-atoms
Carbonyl group = aldehyde = aldose
Carbonyl group = ketone = ketose
Ex: 3C = trioses 5C = pentoses

3. Aldoses

4. Ketoses

5. B. Determination of D or L
4 isomer positions
16 stereo positions
8 will be D
8 will be L
D or L assigned by absolute configuration farthest from carbonyl group
D-glucose

6. Configurations
Predominate form of aldoses/ketoses are not in straight chain
Monosaccharides with 5+ carbons usually cyclize
6-membered rings = pyranose
5-membered rings = furanose
2 anomeric forms of cyclic sugars
 and  forms
Carbonyl carbon = anomeric carbon = chiral center
 form: OH group of the anomeric C is on OPPOSITE side of ring from CH2OH
 form: OH group of the anomeric C is on SAME side of ring from CH2OH

7. C. Configurations
Hexose and pentose can form pyranose or furanose forms
Glucose usually pyranose
Fructose 67% pyranose
Ribose 75% pyranose
Chair and boat conformations

8. D. Sugar derivatives
Chemistry of monosaccharides is largely that of hydroxy and carbonyl groups
Addition of amine - good for support in cell walls
Deoxygenating - used in DNA
Phosphoralation - used in energy storage
1. Redox
Can be oxidized under mild conditions (Ag+, Cu2+)
Can test for sugars: Fehlings (Cu2+) or Tollins (Ag+) test
Only works for aldose sugars

9. 2. Phosphorylation
Important for metabolism
First step in glucose breakdown to obtain energy
Convert to glucose-6-phosphate
Makes sugar anionic
3. Removal of -OH
Where OH unit is replaced by H
Called deoxy sugars
-D-2-deoxyribose
Component of DNA
L-fucose
One of few naturally occurring L sugars

10. Sucrose, maltose, lactose Linkage of 2+ sugars by glycosidic bond
4. Polysaccharides
Sucrose, maltose, lactose
Linkage of 2+ sugars by glycosidic bond
Bond connecting anomeric C to the hydroxyl
Sugars that have anomeric C that have not formed glycosidic bonds = reducing sugars
Can go on to react further
Are in equilibrium ring and linear forms

11. II. More Complex Polysaccharides
Cellulose
Serves structural role
One of most abundant organic cmpds in biosphere
Linear polymer chain (15,000 D-glucose (14))
Water insoluble (but glucose is?!?)

12. B. Carbohydrates Linked to Proteins
Carbohydrate group can be covalently attached to a protein to form a glycoprotein
Component of cell membranes, important for cell adhesion
Human ABO blood has carbohydrates attached to proteins/lipids on surface of red blood cells
All have common foundation (O) antigen
A and B antigen have extra monosaccharide through -1,3 linkage
Use of proper ABO blood group in transfusion critical, otherwise body rejects incompatible blood cells