carbohydrates

2. CARBOHYDRATE CHEMISTRY
BY Dr.Shamim Akram
AP Biochemistry AIMC

4. DEFINITION
• Carbohydrates, or saccharides (saccharo is Greek for
―sugar) are polyhydroxy aldehydes or ketones, or substances
that yield such compounds on hydrolysis.
• Carbohydrates include not only sugar, but also the starches
that we find in foods, such as bread, pasta, and rice.
• The term ―carbohydrate comes from the observation that
when you heat sugars, you get carbon and water (hence,
hydrate of carbon.

5. Carbohydrates Biochemistry
•Carbohydrates are compounds of tremendous
biological importance:
–they provide energy through oxidation
–they supply carbon for the synthesis of cell
components
–they serve as a form of stored chemical energy
–they form part of the structures of some cells and
tissues
•Carbohydrates, along with lipids, proteins, nucleic
acids, and other compounds are known as
biomolecules because they are closely associated with
living organisms.

6. BIOCHEMICAL FUNCTIONS OF CHO
• Nutritional Importance
• Oligosaccharides are part of :
• Cell Membrane with integral proteins
• Antibodies, blood clotting factors.
• Lectins bind cho on cell surface for
recognition, signaling and adhesion
processes
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7. • Glycosaminoglycans (GAGS) are part of extra
cellular matrix(ground substance).
• Ribose and deoxyribose (nucleic acids).
• Ribose is essential part of high energy phosphate
compounds (ATP,GTP,UTP) and second messengers
(cAMP,cGMP) and co enzymes (FMN,FAD,NAD).
• ABO blood group system Antigen.
• Apo B part of lipoproteins
• Heparin anticoagulant
• Glucose oxidized to Glucoronic acid needed for
conjugation of Billirubin(new born).
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8. Glucose (a monosaccharide)
Plants:
photosynthesis
chlorophyll
6 CO2 + 6 H2O C6H12O6 + 6 O2
sunlight (+)-glucose
(+)-glucose starch or cellulose
respiration
C6H12O6 + 6 O2 6 CO2 + 6 H2O + energy

9. Animals
plant starch (+)-glucose
(+)-glucose glycogen
glycogen (+)-glucose
(+)-glucose fats or aminoacids
respiration
(+)-glucose + 6 O2 6 CO2 + 6 H2O + energy

10. CLASSIFICATION:
1- Monosaccharides (simple sugars):
They can not be hydrolyzed into simpler units. E.g.
glucose, galactose,ribose
2- Oligosaccharides (oligo = few): contain from two to
ten monosaccharide units joined in glycosidic bonds.
e.g.
• disaccharides (2 units) e.g. maltose and sucrose and
lactose.
• Maltotriose(3 units)
α-Dextrins(8 units).

11. 3-Polysaccharides (poly = many): Also known as glycans.
They are composed of more than ten monosaccharide
units.
Homopolysacharides:on hydrolysis give only one type of
monomers (starch,glycogen,cellulose) Inulin:
Homopolysacharide of Fructose.
Heteropolysacharides: contain more than two or
more different typep of monosacharides.
GAGs(Mucopolysacharides):Hyaluronic acid
Chondroitin sulfates,Heparin,ABO bg,s.mucoid
Glyco-congugates:Proteoglycans,glycopro.gly.lipid
Mucilages:Agar,Gums,pectins.
.
4-Derived CHO: produced by chemical reactions,
Oxidation products:(glucoronic acid)
Reductionproducts:(Alcoholsorbitol,manitol,glycerol)
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12. Monosaccharides
CLASSIFICATION OF MONOSACCHARIDES
1- According to the number of carbon atoms:
.Trioses, contain 3 carbon atoms.
• Tetroses, contain 4 carbon atoms.
• Pentoses, contain 5 carbon atoms.
• Hexoses, contain 6 carbon atoms.
• Heptoses, contain 7 carbon atoms.
• Octoses. contain 8 carbon atoms.

13. 2- According to the characteristic carbonyl
group (aldehyde or ketone group):
- Aldo sugars: aldoses:
Contain aldehyde group e.g. glucose, ribose,
erythrose and glyceraldehydes.
- Keto sugars: ketoses:
Contain ketone group e.g. fructose, ribulose and
dihydroxy acetone.

14. Forms of Monosaccharides:

15. Trioses:
D- glyceraldehyde Dihydroxyacetone

16. Tetroses:
D - erythrose
Ketose
CH2OH
C = O
H -C – OH
CH2 OH
D - erythrulose

17. Pentoses:

18. Hexoses:

19. Heptoses: is a ketose sugar
D - sedoheptulose

20. It is aptly said that
Glyceraldehyde is the
‘Reference Carbohydrate’