The document discusses carbohydrates, which are a major source of energy composed of carbon, hydrogen, and oxygen. They include monosaccharides (simple sugars), disaccharides (two monosaccharides joined), oligosaccharides (3-10 monosaccharides), and polysaccharides (long chains of monosaccharides). Important monosaccharides include glucose, fructose, and galactose. Disaccharides formed from two monosaccharides include maltose, lactose, and sucrose. Polysaccharides are polymers of monosaccharides and include starch, glycogen, and cellulose. Carbohydrates have important biomedical roles as energy sources and structural components in the body.

1. ATIF MEHMOOD
L E C T U R E R I N R A D I O L O G Y K M U
BIOCHEMISTRY
Carbohydrates

2. Carbohydrates
2
Carbohydrates are
 A major source of energy
from our diet.
 Composed of the
elements C, H, and O.
 Also called saccharides,
which means ―sugars.‖
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Publishing as Benjamin Cummings

3. Carbohydrates
3
Carbohydrates
 Are produced by
photosynthesis in plants.
 Such as glucose are
synthesized in plants from
CO2, H2O, and energy from
the sun.
 Are oxidized in living cells
(respiration) to produce CO2,
H2O, and energy.
Copyright © 2007 by Pearson Education, Inc
Publishing as Benjamin Cummings

4. CARBOHYDRATES
 Carbohydrates are aldehyde or ketone compounds
with multiple(two or more)hydroxyl groups.
 They are polyhydroxylated compounds with
atleast three carbon atoms, with potentially active
carbonyl groups which may either be aldehyde or
ketone groups.
 The term applied to a large number of relatively
heterogeneous compounds found in all animals
and plants.
 Carbohydrates including sugars are also called
saccharides(saccharide=sugar).

5. Types of Carbohydrates
5
The types of carbohydrates are
 Monosaccharide, the simplest carbohydrates.
 Disaccharides, which consist of two monosaccharide.
 Polysaccharides, which contain many monosaccharide.
Copyright © 2007 by Pearson Education, Inc.
Publishing as Benjamin Cummings

6. CLASSIFICATION OF CARBOHYDRATES:
 MONOSACCHARIDES
 DISACCHARIDES
 OLIGOSAACHARIDES
 POLISAACHARIDES

7. Monosaccharides
7
Monosaccharides consist of
 3 to 6 carbon atoms, typically.
 A carbonyl group (aldehyde or ketone).
 Several hydroxyl groups.

8. MONOSACCHARIDES:
 Also called simple sugars ,are those which can not be
hydrolyzed further into simpler forms.
 General formula------------CnH2nOn
 They can be subdivided further ,
 A) Depending upon the number of carbon atoms
they possess ,as
trioses,tetroses,pentoses,hexoses,etc.
 B) Depending upon whether aldehyde(-CHO) or
ketone(-CO) groups are present as aldoses or ketoses

9. Aldoses
9
Aldoses are
monosaccharides
 With an aldehyde group.
 With many hydroxyl
(─OH) groups.
triose (3 C atoms)
tetrose (4 C atoms)
pentose (5 C atoms)
hexose (6 C atoms)
O
║
C─H aldose
│
H─ C─OH
│
H─ C─OH
│
CH2OH
Erythose, an aldotetrose

10. Ketoses
10
Ketoses are
monosaccharides
 With a ketone group.
 With many hydroxyl
(─OH) groups.
triose (3 C atoms)
tetrose (4 C atoms)
pentose (5 C atoms)
hexose (6 C atoms)
CH2OH
│
C=O ketose
│
H─ C─OH
│
H─ C─OH
│
H─C─OH
│
CH2OH
Fructose, a ketohexose

11. Learning Check
Identify each as aldo- or keto- and as tetrose, pentose,
or hexose:
A B
H
CH2OH
OHC
H
H
H
OH
OH
OH
C
C
C
HC
O
CH2OH
HHO
CH2OH
O
H OHC
C
C
11

12. Solution
12
A. aldohexose
B. ketopentose

13. D-Glucose
13
D-glucose is
 Found in fruits, corn
syrup, and honey.
 An aldohexose with
the formula
C6H12O6.
 Known as blood
sugar in the body.
 The monosaccharide
in polymers of
starch, cellulose,
and glycogen.
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Publishing as Benjamin Cummings

14. Blood Glucose Level
14
In the body,
 Glucose has a
normal blood
level of 70-90
mg/dL.
 A glucose
tolerance test
measures blood
glucose for
several hours
after ingesting
glucose.
Copyright © 2007 by Pearson Education, Inc Publishing as Benjamin Cummings

15. D-Fructose
D-fructose
 Is a ketohexose
C6H12O6.
 Is the sweetest
carbohydrate.
 Is found in fruit
juices and honey.
 Converts to
glucose in the
body.
H OH
CH2OH
C
HO
H OH
H
C
O
C
C
CH2OH
D-Fructose
15
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Publishing as Benjamin Cummings

16. D-Galactose
D-galactose is
 An aldohexose
C6H12O6.
 Not found free in
nature.
 Obtained from lactose,
a disaccharide.
 A similar structure to
glucose except for the
–OH on C4.
H
H
H OH
CH2OH
C
HO
HO HC
OH
C
C
O
C H
D-Galactose
16

17. General
formula
Aldosugars Ketosugars
Trioses
(C3H6O3)
Glyceraldehydes Dihydroxyacetone
Tetroses
(C4H8O4)
Erythrose Erythrulose
Pentoses
(C5H10O5)
Ribose Ribulose
Hexoses
(C6H12O6)
Glucose Fructose

18. DISACCHARIDES:
 Are those sugars which yield two molecules of the same
or different molecules of monosaccharide on hydrolysis.
 General formula-----------Cn(H2O)n-1
 Examples:
 Maltose: Yields 2 molecules of glucose on hydrolysis.
 Lactose: Yields one molecule of glucose and one
molecule of galactose on hydrolysis.
 Sucrose: Yields one molecule of glucose and one
molecule of fructose on hydrolysis.

19. Important Disaccharides
19
A disaccharide
 Consists of two monosaccharide.
Monosaccharide Disaccharide
Glucose + glucose maltose + H2O
Glucose + galactose lactose + H2O
Glucose + fructose sucrose + H2O

20. Maltose
20
Maltose is
 A disaccharide also known as malt sugar.
 Composed of two D-glucose molecules.
 Obtained from the hydrolysis of starch.
 Linked by an -1,4-glycosidic bond formed from
the
 −OH on C1 of the first glucose and −OH on C4
of the second glucose.
 Used in cereals, candies, and brewing.
 Found in both the - and β - forms.

21. Formation of Maltose
21
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22. Lactose
Lactose
 Is a disaccharide of β-
D-galactose and α- or
β-D-glucose.
 Contains a β -1,4-
glycosidic bond.
 Is found in milk and
milk products.
22
α-form
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23. Sucrose
23
Sucrose or table sugar
 Is obtained from sugar cane and sugar beets.
 Consists of α-D-glucose and β-D-fructose..
 Has an α,β-1,2-glycosidic bond.
α-D-glucose
β-D-fructoseCopyright © 2007 by Pearson Education, Inc.
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24. OLIGOSAACHRIDES:
 Are those which yield 3 to 10 monosaccharides units
on hydrolysis,e.g.Maltotriose.
 These are short chain condensation products of two
to ten monosaccharide units or residues joined to
each other covalently through O- glycoside bonds or
linkages.
 Some oligosaccharides are,
 α-dextrins (polymers of eight glucose units)
 Maltotriose (has three glucose units)
 Isomaltose

25. Carbohydrates
Polysaccharides
25
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Publishing as Benjamin Cummings

26. Polysaccharides
Polysaccharides
 Are polymers of D-glucose.
 Include amylose and
amylopectin, starches made
of α-D-glucose.
 Include glycogen (animal
starch in muscle), which is
made of α-D-glucose.
 Include cellulose (plants and
wood), which is made of
β-D-glucose.
O
CH2OH
OH
OH
OH
OH
26
α-D-glucose

27. POLYSACCHARIDES:(GLYCANS)
 Are those which yield more than ten molecules of
monosaccharides on hydrolysis.
 General Formula---------------(C6H10O5)n
 Polysaccharides are further divided into two groups,
 A) Homopolysaccharides (homoglycans):
Polymer of same monosaccharide units.
 Examples:
Starch, glycogen, insulin, cellulose, dextrins, dextrans.
 B) Heteropolysaccharides (heteroglycans):
Polymer of different monosaccharide units or their derivatives.
 Examples:
Mucopolysaccharides (Glycosaminoglycans)

28. BIOMEDICAL IMPORTANCE OF
CARBOHYDRATES:
 Chief source of energy
 Constituents of compound lipids and conjugated proteins
 Certain carbohydrate derivates are used as drugs like
cardiac glycosides/antibiotics
 Lactose principal sugar of milk—in lactating mammary
glands.
 Degradation products utilized for the synthesis of other
substances such as fatty acids, cholesterol, amino acids
etc.
 Derangement of glucose metabolism is seen in Diabetic
mellitus.