carbohydrate chemistry biochemistry notes for physiotherapy students.

1. Chemistry of
Carbohydrates

2. Functions of Carbohydrates
•1. sources of energy
•Carbohydrates are the main sources of energy in the
body
•2.Storage form of energy
• glycogen in animals are the storage form of energy
•3. Structural basis of many organisms
•Carbohydrates are the component of many cells
•4. Dietray fibers prevents constipation and colon
cancer
•5. Heparin as anticoagulant

3. Definition
•Carbohydrates are polyhydroxy aldehydes or
ketones or compounds which yield these on
hydrolysis

4. classification
1.Monosaccharides
2.Disaccharides
3.Oligosaccharides
4.polysaccharides

5. monosaccharides
•Simplest carbohydrates
•Cannot be further hydrolysed to smaller units
•Molecules having only one sugar group are called
monosaccharides
•They cannot be further hydrolysed into smaller units
•Eg. Glucose, Fructose

6. Classification
•Based on functional group (aldehyde or ketone)
present
1. Aldoses : monosaccharides containing aldehyde
group are called as aldoses
•Eg. Glucose, galactose
2. Ketoses : monosaccharides containing keto group
are called ketoses
•Eg. Fructose, ribulose

7. •Based on number of carbon atoms present
1.Trioses :3 carbon, eg. Glyceraldehyde
2.Tetroses : 4 carbon , eg. Erythrose
3.Pentoses : 5 carbon, eg. Ribose
4.Hexoses : 6 carbon, Eg. Glucose
5.Heptoses : 7 carbon, Eg. sedoheptulose

8. DISACCHARIDES
•When two monosaccharides are combined
together
•by glycosidic linkage, a disaccharide is formed. The
•important disaccharides are
•1. Sucrose (glucose and fructose)
•2. Maltose (2 glucose)
•3. isomaltose
•4. Lactose (glucose and galactose)

9. Oligosaccharides
•Contains 3-10 monomeric units bounded by
glycosidic bonds

10. polysaccharides
Polysaccharides contain more than 10 monomeric units
bounded by glycosidic bonds
• They may be
• 1. Homoglycans (homopolysaccharides) are composed
of single kind of monosaccharides, e.g. starch, glycogen
and cellulose.
• 2. Heteroglycans (heteropolysaccharides) are
composed of two or more different monosaccharides, e.g.
hyaluronic acid, chondroitin sulphate.

12. monosaccharides
• Simplest carbohydrates
• Cannot be further hydrolysed to smaller units
• Molecules having only one sugar group are called monosaccharides
• They cannot be further hydrolysed into smaller units
• Eg. Glucose, Fructose

14. Glucose
•Glucose is the most predominant sugar in
human body. It is the major source of energy.
It is present in blood

15. Structure of glucose
1.Open chain form (straight chain)
2.Ring structure
3.Boat or chain form

16. Structure of Glucose
1. Open chain form (straight chain)

17. Isomerism in carbohydrates
•1. structural isomerism
•2. stereoisomerism

18. 1. structural isomerism
•Structural isomers have same molecular formula,
but different structures
•A) functional isomerism : isomers with different
functional groups
•Glucose (contains aldehyde group)
•Fructose (contains ketone group)

19. B) chain isomerism
•Isomers with different arrangement of carbon
atoms
•Eg. Maltose and isomaltose

20. c) Positional isomerism
•Isomers with same carbon chain but differ in
position of substituted group
•Eg. Glucose-1-phosphate and glucose-6-
phosphate

21. 2. stereoisomerism
•Compounds having same structural formula,
but differing in spatial configuration are known
as Stereoisomers
•Asymmetric carbon means that four different
groups are attached to the same carbon

22. a. Geometric isomerism
• Due to the arrangement of atoms around the double bond is termed as
Geometric isomerism
• Geometric isomers have a double bond

23. b.Optical Activity
• The presence of asymmetrical carbon atom causes optical
activity.
• i. Diastereo-isomers of Glucose
• Configurational changes with regard to C2, C3 and C4 will
produce eight different monosaccharides.
• Out of these, only 3 are seen in human body. They are
Glucose, Galactose and Mannose.

24. •ii. Epimerism of Aldoses
•When sugars are different from one another,
only in configuration with regard to a single
carbon
•atom, they are called epimers. For example,
glucose and mannose are an epimeric pair
which differ only with respect to C2

25. iii. Enantiomerism (D and L isomerism)
D and L isomers are mirror images of each other

26. iv. Anomerism
H
H

27. •Orientation of OH and H around the
anomeric carbon results in alpha and beta
forms.
•In Alpha form H is above the ring and OH is
below the ring
•In Beta form it is reversed

28. mutarotation
•The change in optical rotation of optical
isomers with time is called mutarotation
•Reason
•Mutarotation is due to the conversion of some
alpha D-Glucose molecule to beta D-Glucose and
vice versa to attain equilibrium

29. Galactose
•Galactose is a constituent of lactose (milk sugar)

30. Glycosidic bond or glycosidic linkage
• Definition
• It is the bond between the OH group of an anomeric carbon atom of a
carbohydrate and OH group of another carbohydrate or a non carbohydrate
, with loss of water molecule
• Significance
• Glycosidic bonds are responsible for the formation of higher carbohydrates
• (disaccharides, oligosaccharides, polysaccharides)

31. Glycosides: assignment

33. Disaccharides
•When two monosaccharides are combined together
by glycosidic linkage, a disaccharide is formed.
Theimportant disaccharides are
•1. Sucrose
•2. Maltose and isomaltose
•3. Lactose.

34. •Sucrose
•i. It is the sweetening agent known as cane sugar.
It is present in sugarcane and various fruits.
•ii. Sucrose contains glucose and fructose.
•Sucrose is not a reducing sugar;

35. •Sucrose is implicated in dental caries
•People who consume sugar sweets are more
susceptible to dental caries

36. •Invert sugar
•Change in specific rotation is called as inversion
•Sucrose is dextrorotatory in nature.
•When sucrase enzyme acts on sucrose, it is
converted into a mixture of glucose and fructose.
•So resultant mixture of glucose and fructose exhibit
a laevorotation

37. •Dextrorotatory sucrose is converted to
laevorotatory mixture of glucose and fructose
is known as inversion
•Mixture of glucose and fructose is called as
invert sugar

38. •Lactose
•It is the sugar present in milk. It is a
reducing
•disaccharide. On hydrolysis lactose
yields
•glucose and galactose.

39. •Maltose
•i. Maltose contains two glucose
residues
•It is a reducing disaccharide

40. Reducing sugar and Non Reducing sugar.
• Free aldehyde or keto group of anomeric carbon is responsible for
reducing property.
•Those sugars which act as reducing agents are
called reducing sugars
• All monosaccharides are reducing sugars ; because they have free
anomeric carbon
• Lactose and matose are reducing sugars
• Sucrose is a non reducing sugars

41. Benedict's test
•Test for reducing sugar (glucose, fructose, lactose)

42. 5 ml
8 drops of
sugar solution

43. •Observation
•Red colour precipitate is formed

44. • Significance