Science

1. CARBOHYDRATE STRUCTURE AND
FUNCTION
SAMUEL ACQUAH (BSc.,MSc.,MSc.,PhD)
Associate Professor
Department of Medical Biochemistry
School of Medical Sciences
University of Cape Coast
Cape Coast, Ghana
Email: s.acquah@uccsms.edu.gh
Mobile: 0242341428
GEM 202 COORDINATOR

2. LECTURE OBJECTIVES
At the end of this lecture, you should be able to:
• Define carbohydrate and give examples
• State and explain the functions of carbohydrate
• Describe various reactions of carbohydrate and
discuss their medical application potentials

3. DEFINITION
• Polyhydroxy aldehydes or ketones, or substances
that yield such compounds on hydrolysis.

4. FUNCTIONS
• Storage of energy
• Energy source
• Components of lipid, protein and
nucleic acids
• Glycoconjugates are important in cell
walls and extracellular structures
• Important in cellular recognition,
adhesion and communication

5. BASIS FOR FUNCTIONAL VERSATITLITY
• Presence of at least one asymmetric
center
• Ability to exist in linear or ring structure
• Ability to form polymeric structure
(glycosidic bonds)
• Capacity to form hydrogen bonds

6. CLASSIFICATION
• Monosaccharides (e.g. glucose,
fructose)- cannot be hydrolyzed into
simpler forms.
• Oligosaccharides (2-10 units e.g.
maltose, sucrose, maltotriose)
• Polysaccharides (>10 units e.g. starch,
dextrin, glycogen)

7. BASIS OF CLASSIFICATION OF
MONOSACCHARIDES
Number of carbon atoms
Functional group
Configuration at penultimate carbon (D & L)
Direction of rotation of plane polarized light (-
& + designations)

8. BASIS OF CLASSIFICATION CONT’D-epimers, diastereomers

9. BASIS OF CLASSIFICATION CONT’D-enantiomers

10. REACTIONS OF CARBOHYDRATES
-hemiacetal/ketal and acetal/ketal – ring formation
O O
Pyran
Furan

11. HEMIACETAL- ring structures
mutarotation

12. HEMIKETAL

13. ACETAL AND KETAL FORMATION

14. REACTION CONT’D
-some sugars are non-reducing

15. POLYMERIZATION
(amylose, amylopectin, cellulose)

16. REACTION WITH A BASE
(epimerization, enediol re-arrangement)

17. REACTIONS CONT’D
-oxidation

18. REACTION CONT’D
-oxidation, reduction
(or NaBH4)

19. REACTION WITH NITRIC ACID
-aldaric acid

20. RUFF DEGRADATION

21. CARBON-CHAIN ELONGATION
(Killiani-Fischer synthesis)

22. OSAZONE FORMATION
(reaction with phenylhydrazine)

23. OTHER REACTIONS

24. SUMMARY
• Carbohydrates are versatile biomolecules:
-functions
-chemical constituents
-reactions
- health and wellbeing of mankind

25. REFERENCES
• David L. Nelson & Michael M. Cox (2008).
Lehninger’s Principles of Biochemistry. Fourth
edition. Chapter 7, pp. 238-268.
• Robert K. Murray, David Bender, Peter Kennelly,
Victor W. Rodwell and P. Anthony Weil. (2003).
Harper’s Illustrated Biochemistry. Twenty-sixth
edition. Chapter 13, pp. 102-110.
• Basic organic chemistry textbooks