1. CARBOHYDRATES
MNR MEDICAL COLLEGE & HOSPITAL
Dr Anurag Yadav
MBBS, MD
Assistant Professor
Department of Biochemistry
Instagram page –biochem365
Email: dranurag.y.m@gmail.com

2.  Definition
 Classification
 Isomers
 Chemical properties

3.  Carbohydrates are polyhydroxy alcohols aldehyde
or ketone OR compounds which yield these on
hydrolysis

4. CARBOHYDRATE
 Source of energy
 Storage form of energy (Starch & Glycogen)
 Excess carbohydrate is converted to fats
 Component of cell membrane
 Non digestible carbohydrates (cellulose, agar) serve as
dietary fibers
 Constituent of DNA & RNA (ribose, deoxyribose)

5. Classification
 Monosaccharides
 Disaccharides
 Oligosaccharides
 Polysaccharides

6.  Monosaccharides
 Simple sugars
 Having one sugar unit
 Cannot be further broken down
 Glucose, Fructose, Galactose
 Disaccharides
 2 monosaccharide unit joined together
 Glycosidic bond
 Sucrose – Glucose+ Fructose
 Maltose – Glucose+Glucose
 Lactose – Glucose+Galactose

7.  Oligosaccharides
 2-10 monosaccharide unit joined together
 Glycosidic bond
 Glyceraldehyde
 Erythrose, Erythrulose
 Arabinose, Xylose, Ribose, Xylulose, Ribulose
 Glucose, Galactose, Mannose, Fructose

8. Polysaccharides
 Many monosaccharide units joined together
 Homopolysaccharides
 Composed of single type of monosaccharide
 Starch, Glycogen
 Heteropolysaccharides
 Composed of two or more different type of monosaccharide
 Agar, Gum, Hyaluronic acid, Keratan sulphate

10.  Three Representations of Glucose Structure

11. STERIOISOMERISM
 Same molecular formula & same structure but they
differ in configuration (arrangement of their atoms in
space)
 D & L isomerism
 Optical isomerism
 Epimerism
 Anomerism

12.  D & L isomerism
 Depends upon the configuration of the asymmetric carbon
farthest to the carbonyl carbon (penultimate carbon atom)
 D-sugars are naturally occurring sugars and body
can metabolize only D-sugars

15. OPTICAL ISOMERISM
 The isomer that rotates the plane of polarized light to
the left (counterclockwise) is called levorotatory (l).
The other isomer that rotates the light to the right
(clockwise) is called dextrorotatory (d).
D Glucose +52.7 Dextrorotatory d/+
D Fructose -92 Levorotatory l/-

16. EPIMERISM
 When sugars differ from one another only in
configuration with regard to a single asymmetric C atom
other than reference carbon atom.

17. ANOMERISM
 Alpha – The OH group attached to C1 is below the
plane of the ring
 Beta - The OH group attached to C1 is above the plane
of the ring

18. ANOMERS-ALPHA AND BETA

20. MUTAROTATION
 Change in specific optical rotation by interconvertion
of alpha & beta forms of D-Glucose
 Alpha D glucose - +112o
 Beta D glucose - +19o
 Equilibrium - 1/3 alpha anomers & 2/3 beta anomers
(+52.5o)

22. CHEMICAL PROPERTIES
 Enediol formation – alkaline solution
 BENEDICT’S TEST
 Furfural derivatives – concentrated Acids
 Osazone formation
 Oxidation – uronic acid
 Reduction to form alcohol

23.  Enediol formation – alkaline solution
 BENEDICT’S TEST

24. • BENEDICT’S TEST

25. Osazone Formation
 All reducing sugars will form osazones with excess of
phenylhydrazine when kept at boiling temperature.
 Osazones are insoluble

27. Oxidation of Sugars
 Under mild oxidation conditions -- aldehyde group is
oxidized to carboxyl group to produce aldonic acid
 Glucose --Gluconic Acid,
 Mannose -- Mannonic Acid And
 Galactose -- Galactonic Acid

28.  When aldehyde group is protected -- last carbon
becomes COOH group to produce uronic acid
 Glucose – Glucuronic Acid,
 Mannose To Mannuronic Acid And
 Galactose To Galacturonic Acid.
 The glucuronic acid is used by the body for
conjugation

29.  Under strong oxidation conditions -- first and last
carbon atoms are simultaneously oxidized to form
dicarboxylic acids (saccharic acids)
 Glucose -- Glucosaccharic Acid,
 Mannose To Mannaric Acid
 Galactose To Mucic Acid
 Mucic Acid test --- Galactose

31. Furfural Derivatives
 Monosaccharides when treated with concentrated
sulfuric acid undergo dehydration with the removal of 3
moleculesof water.
 Therefore hexoses give hydroxymethyl furfural and
pentoses give furfural.
 The furfural derivative can condense with phenolic
compounds to give colored products.
 Molisch's test

33. Reduction to Form Alcohols
 Reducing agents, such as sodium amalgam
 Glucose ---Sorbitol;
 Mannose ---- Mannitol;
 Fructose --- Sorbitol And Mannitol
 Galactose --- Dulcitol And
 Ribose -- Ribitol.

34.  Sorbitol, mannitol and dulcitol -- identify bacterial
colonies.
 Mannitol --- reduce intracranial tension by forced
diuresis. The osmotic
 sorbitol and dulcitol when accumulated in abnormal
amounts, produces changes in tissues e.g. cataract of
lens.

35. Glycosides
 When the hemiacetal group (hydroxyl group of the
anomeric carbon) of a monosaccharide is condensed
with an alcohol or phenol group, it is called a glycoside
 Digitonin is a cardiac stimulant.
 Phlorhizin is used to produce renal damage in
experimental animals.
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36. Amino Sugars
 Amino groups substituted for hydroxyl groups
 Added to the second carbon atom of hexoses
 Glucosamine, Galactosamine -- chondroitin of cartilage,
bone and tendons

37. Deoxy Sugars
 Oxygen of the hydroxyl group may be removed to form
deoxy sugars

38. DISACCHARIDES
Sucrose
 sugarcane and various fruits
 Glucose and Fructose.
 Sucrose is not a reducing sugar; and it will not
form osazone
 Becomes reducing after hydrolysis

39. Invert sugar
 Sucrose (optical rotation +66.5°)
 Hydrolysis -- glucose (+52.5°) and one molecule of
fructose (–92°)
 The products will change the dextrorotation to
levorotation, or the plane of rotation is inverted
 Enzyme producing hydrolysis of sucrose is called
sucrase or invertase

40. Lactose
 sugar present in milk.
 It is a reducing disaccharide
 Beta glycosidic linkage - beta-1,4 glycosidic linkage
 "hedgehog“, "pincushion with pins“, “powder puff” –
Osazones

41. Maltose
 alpha-1,4 linkage
 reducing disaccharide

42. POLYSACCHARIDES
1. Homoglycans are composed of single kind of
monosaccharides, e.g. starch, glycogen, Inulin and
cellulose.
2. Heteroglycans are composed of two or more
different monosaccharides, e.g. hyaluronic acid,
chondroitin sulfate.

43. Starch
 Storage form in plants
 Sources: Potatoes, tapioca, rice, wheat
 Amylose and Amylopectin
 Amylose soluble part is made up of glucose units with
alpha-1,4 glycosidic linkages
 unbranched long chain
 amylopectin insoluble part made up of glucose units, but
is highly branched with
 Branching alpha-1,6 linkage

44.  Iodine test for starch – deep blue colour
 Salivary amylase and pancreatic amylase act at
random on alpha-1,4 glycosidic bonds to split starch
into smaller units (dextrins), and finally to alpha-
maltose

45. Glycogen
 Storage carbohydrate in animal
 Stored in liver and muscle
 Glycogen is composed of glucose units joined by alpha-1,4
links in straight chains. It also has alpha-1,6 glycosidic
linkages at the branching points
 Molecular weight of glycogen is about 5 million.
 Innermost core of glycogen contains a primer protein,
Glycogenin.
 Glycogen is more branched and more compact
than amylopectin

47. STARCH GLYCOGEN
STORAGE FORM OF
CARBOHYDRATES IN PLANTS
STORAGE FORM OF
CARBOHYDRATES IN ANIMALS
STORED IN LIVER & MUSCLE
COMPOSED OF AMYLOSE
(Unbranched) & AMYLOPECTIN
(Highly Branched)
COMPOSED OF GLUCOSE UNITS
JOINED BY alpha 1-4 & alpha 1-6
bonds
LESS BRANCHED THAN
GLYCOGEN
MORE BRANCHED THAN
STARCH
NO CORE PROTEIN CORE PROTEIN IS PRESENT
BLUE COLOUR WITH IODINE
TEST
RED COLOUR WITH IODINE

48. CELLULOSE
 It is supporting system in plants
 Made of glucose with beta1,4 linkage.
 It is a straight structure, with NO branching
points.
 Hydrolysed by enzyme cellobiase.

50. INULIN
 It is a homopolysaccheride
 Composed of D-fructose with repeating beta-1,2
linkages
 Present in tuber, onion, garlic
 Clinically useful to find the renal clearance &
glomerular filtration rate.

51. HETEROGLYCANS
 Mucopolysaccharides or glycosamino glycans (GAG)
are heteropolysaccharides, containing uronic acid
and amino sugars
 charged groups Acetylated amino groups, sulfate and
carboxyl groups
 Charged groups attract water molecules and so they
produce viscous solutions
 hyaluronic acid, heparin, chondroitin sulfate,
dermatan sulfate and keratan sulfate.

53. Mucopolysaccharidoses
 Hyaluronic acid -- connective tissues, tendons,
synovial fluid and vitreous humor, lubricant in joint
cavities
 Repeating units of N-Acetyl-glucosamine→ beta-1, 4-
Glucuronic acid → beta-1-3-N-Acetyl glucosamine

54. Heparin
 Anticoagulant -- prevent intravascular coagulation
 Heparin is present in liver, lungs, spleen and
monocytes
 repeating units of sulphated glucosamine → alpha-1,
4-L-iduronic acid

55. Chondroitin Sulfate
 Ground substance of connective tissues widely
distributed in cartilage, bone, tendons, cornea and skin
 Repeating units of glucuronic acid→ beta-1,3-N-acetyl
galactosamine sulfate

56. Keratan Sulfate
 Repeating units are galactose and N-acetyl
glucosamine in beta linkage.
 It is found in cornea and tendons

57. Dermatan Sulfate
 L-iduronic acid and N-acetyl galactosamine in beta-1,
3 linkages
 Found in skin, blood vessels and heart valves

60. Dr Anurag Yadav
MBBS, MD
Assistant Professor
Department of Biochemistry
Instagram page –biochem365
Email: dranurag.y.m@gmail.com