1. Dr. Sohaib F. Khawja,
(Gold Medalist)
Prof . of BIOCHEMISTRY
MMDC Multan
Carbohydrates

2. Carbohydrates
 Definitions
 Classification
 Functions
 Monosaccharides
 Disaccharide
 Polysaccharides
 Homopolysaccharides
 Heteropolysaccharides
 Glycosaminoglycans
 Proteoglycans
 Mucopolysaccharidoses
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4. Carbohydrates
(Glycomes)
CARBOHYDRATES are polyhydroxy aldehydes or ketones .
The word signifies hydrate of carbon. (Saccharide= sugar)
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The glycomics is the study of all types of carbohydrates

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7. CLASSIFICATION OF CARBOHYDRATES
 Monosaccharides:
Simple sugars, not further hydrolyzed; ribose, glucose,
fructose, galactose, mannose.
 Disaccharides:
On hydrolysis yield 2 units of monosaccharides; lactose,
sucrose, maltose, isomaltose and trehalose.
 Oligosaccharides:
Consists of 3-10 units of monosaccharides i.e .
Trisaccharides (Malto-triose, raffinose), tetrasaccharides
(stachyose), etc.
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I. Based on Hydrolysis (Important)

8.  Polysaccharides: Contain more than 10 units of
monosaccharides. They may be glucosan or fructoson
Furhter divided:
 Homopolysaccharides:
Include one type of monosaccharides:- starch, glycogen,
cellulose, dextrins, dextran, Innulin.
 Heteropolysaccharides:
Include different types of monosaccharides with prosthetic
groups:- heparin, hyaluronic acid, chondroitin sulfate,
agar, pectins.
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9. II. Based on Number of Carbon Atoms.
1. Trioses 3C. Glyceraldehyde. DHA.
2. Tetroses 4C. Erythrose, erythrulose.
3. Pentoses 5C. Ribose, ribulose.
4. Hexoses 6C. Glucose, fructose, galactose.
5. Heptose 7C. sedoheptose, sedoheptulose.
6. Dimmers 2 units. Lactose, sucrose, maltose.
7. Polymers > 10 units. Starch, glycogen, inulin,cellulose.
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10. III. Based on Active Groups.
1. Aldehydes: Glucose, galactose, ribose, etc.
2. Ketones : Fructose, ribulose, erythrulose.
IV. Based on Reducing Properties.
1. Reducing carbohydrates:
monosaccharides and disaccharides except sucrose.
2. Non reducing carbohydrates:
sucrose and all polysaccharides
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11. V. Based on General Characteristics.
Sugars Starches
1. Sweet in taste Tasteless
2. Crystalline form Amorphous
3. Make true solutions Make colloidal solutions
4. Smaller in size Larger in size
5. Low molecular weight Higher molecular weight
6. Reducing in properties Non reducing in properties
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VI . Based on Functions
1. Nutritional Monosaccharides, disaccharides, starch, glycogen.
2. Structural Cellulose, liginins, chitin, agar etc.
3. Anticoagulant: Heparin (mucopolysaccharides).
4. Lubricative Hyaluronic acid in joints.
5. Energy reservoir: Starch (plants) and glycogen (liver & muscles).
VII. Based on Digestion
1. Digestible Disaccharides, Starch, Glycogen.
2. Non digestible Cellulose, inuline, Agar, Pectins.

13. Functions
 Immediate Source of Energy, 4.1 Cal / gm. (60-70%):- have proteins
Sparing action.
 Lactose of milk is chief source of energy for babies.
Fructose provides energy to sperms.
 Provides bulk to the food, 300 – 400 gms / day
Takes part in structure of cell membranes
 Glycosaminoglycans act as lubricant in joints and structure
 Heparin (Glycosaminoglycans) acts as an anticoagulant.
 Ribose & Deoxyribose take part in Nucleic Acids formation.
 Form high energy compounds: ATP, CTP, UTP.
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14. Cellulose present in diet, is not digested but
performs following functions
Increases Intestinal Motility, prevents constipation
Lowers cholesterol level.
Lowers the incidence of GIT cancers.
Improves glucose tolerance by body
Eliminates intestinal bacterial toxins
Adds weight of foodstuff ingested & gives
a sensation of stomach fullness (Satiety value)
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15. Demerits of cellulose:
 Loss of proteins
 Loss of minerals
 Gases & discomfort
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18. Carbohydrates
Monosaccharides
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Pentoses Hexoses

19. PENTOSES of physiological importance
Sugars Occurrence Biochemical Importance
D-Ribose Nucleic Acids (RNA,DNA) Form Nucleic Acids, Co Enzymes
D- Ribulose Formed in metabolic processes Is intermediate of HMP Shunt
D – Arabinose Gums & Plum Constituents of Glycoproteins
D- Xylose Wood Gums Constituent of Glycoproteins
Proteoglycans, GAGs
D- Lyxose Heart Muscle Human heart muscle
L-Xylulose In Uronic Acid Pathway Found in Urine essential pentosuria
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20. HEXOSES of physiological importance
Sugars Occurrence Biochemical Importance
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D - Glucose
Fruit Juices
Hydrolysis of Starch
Cane Sugar
Maltose & Lactose
Basic sugar of body
Provides sweet taste to food
Maintains blood glucose level
Main source of energy to brain
Hyperglycemia & Glycosuria in DM
D - Fructose Fruit Juices, Honey
Hydrolysis of sucrose
Hydrolysis of Inulin
Can be changed to Glucose
Can provide energy to body & Sperms
Compound of HMP shunt
Hereditary fructose intolerance leads to
fructose accumulation & hypoglycemia
D - Galactose Hydrolysis of Lactose Can be changed to Glucose
Can provide energy
Synthesis in Mammary gland
Constituents of Glyco - Proteins
Constituents of Glyco - Lipids
Can cause Galactosemia & Cataract
D - Mannose Hydrolysis of plants
Hydrolysis of gums
Constituents of many glycoproteins

21. Killiani-Fishcher synthesis
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Enantiomers
(Mirror images)
Epimers

23. Mutarotation of glucose showing anomers
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A. Fisher projections B. Haworth projections

24. D-glucose can cyclize in two
ways forming either furanose or
pyranose structures
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25. Chair and boat conformations of a pyranose sugar
2 possible chair conformations
of b-D-glucose
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26. Special monosaccharides: amino sugars
Constituents of mucopolysaccharides
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Isomerism and its types
Isomers
Epimers
Anomers
Enantiomers
&
Mutarotation

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Chemical Properties of Monosaccharides
Osazone Formation
Conversion to Alcohols
Oxidation to sugar acids
Reducing properties
Formation of glycosides
Formation of esters
Formation of Amino sugar

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Derivatives of monosaccharides

30. Carbohydrates
Disaccharides
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Sucrose = Glucose + Fructose
Lactose = Glucose + Galactose
Maltose = Glucose + Glucose
Isomaltose = 1 – 6 Glucose dimer
Trehalose = 1 – 1 Glucose dimer
Lactulose = Galactose + Fructose
The last one is senthetic. Also present in
heated milk, used as anticonstipation

31. Disaccharides
Sugars Occurrence Biological Importance
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Lactose Milk May occur in urine in
pregnancy
Provides energy to infants
Helps in absorption of Ca & P
Lactase deficiency causes lactose intolerance
Sucrose Cane and beat sugar,
Surghum, Pineapple, Carrot
roots
Provides sweet taste to food Non Reducing
sugar is its property Provides energy to the
tissues
In sucrase deficiency, malabsorption leads to
diarrhea
Maltose Hydrolysis of Starch
Germinating cereals and malt
Converted to Glucose by Maltase
Provides energy in body

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33. Differentiation of Lactose & Sucrose
Lactose Sucrose
Known as milk sugar Common table sugar ( cane sugar)
D- glucose + D-galactose D-glucose+ D- fructose
Joined by glycosidic linkage (ß1-4) Joined together by α1 – 2
Hydrolyzed to glucose & galactose Hydrolyzed to glucose & fructose
Specific enzyme is lactase (int. juice) Specific enzyme sucrase (invertase)
Dextrorotatory disaccharide Dextrorotatry,hydrolytics levorotatory
Reducing sugar in property Non-reducing sugar
Benedict’s test exhibits positive Benedict’s test is negative
lactosazone crystal “ hedge hog shape” Can not form osazone crystals
Synthesized in mammary glands Not formed in body
In lactating mother, may be lactosuria Not such a case.
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34. Carbohydrates
Polysaccharides
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Homopolysaccharides Heteropolysaccharides

35. Carbohydrates
Homopolysaccharides
(Homoglycans)
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Starch
Glycogen
Dextrins
Cellulose
Inulin
Chitin

36. Starch
 Most common storage polysaccharide in
plants
 Composed of 10 – 30% a-amylose and
70-90% amylopectin depending on the
source
 The chains are of varying length, having
molecular weights from several
thousands to half a million
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37. STARCH FORMS
Amylose Amylopectin
1. Occurs 15-20% Occurs 80-85%
2. Low mol . wt. approx. 60,000 High mol. wt. 500,000
3. Soluble in water Insoluble in water
4. Unbranched & straight chain Structurally moderately branched
5. 250-300 D – glucose units More D – glucose units
6. Joined by α1 – 4 linkage Has α1 – 4 glycoside bonds
7. No α1 – 6 linkage Branch point α1-6 link. Approx -80 branches.
One branch after every 24-30 glucose units.
8. Gives blue color with iodine solution. Reddish – violet color with I2 solution.
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38. Hydrolysis of starch
Course of Hydrolysis Reaction with I2
Starch Blue
Soluble starch Blue
Amylo dextrin Purple
Erythrodextrin Red
Achroodextrin Color less
Maltose --------
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39. Amylose and amylopectin are the 2 forms of starch. Amylopectin is a
branched structure, with branches occurring every 12 to 30 residues
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40. Glycogen
 Also known as animal starch
 Stored in muscle and liver
 Present in cells as granules (high MW)
 Contains both a(1,4) links and a(1,6) branches at
every 8 to 12 glucose unit
 Complete hydrolysis yields glucose
 Glycogen with iodine test gives a red-violet color
 Hydrolyzed by both a and b-amylases and by
glycogen phosphorylase
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41. STARCH AND GLYCOGEN
A.Common features:
1. Both are homopolysaccharides.
2. Both are polymers of glucose.
3. Both are tasteless & large in size.
4. Both give no aldo & keto reactions.
5. Both are hydrolyzed by amylase.
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Starch glycogen
1. In plant kingdom Occurs in animal kingdom
2. Less branched Highly branched (tree like)
3. Has amylose, amylopectine -- Nil --
4. Not stored as such in body Stored in body
5. No inherited disorder Glycogen storage diseases
6. Iodine test gives blue color Iodine test gives red color
B.Distinguishing Features:

43. Cellulose
 Polymer of b-D-glucose attached by b(1,4) linkages
 Yields glucose upon complete hydrolysis
 Partial hydrolysis yields cellobiose
 Most abundant of all carbohydrates
○ Cotton flax: 97-99% cellulose
○ Wood: ~ 50% cellulose
 Gives no color with iodine
 Held together with lignin in woody plant tissues
 Beneficial effects: are discussed
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44. Side effects of Fiber (Cellulose)
i. Absorption of proteins is adversely effected.
ii. The intestinal absorption of minerals
(Ca, P, Mg) is decreased
iii. Intestinal bacteria ferment some fibers causing
flatulence and discomfort.
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45. Inulin
 B-(1,2) linked fructofuranoses
 Linear only; no branching
 Lower molecular weight than starch
 Colors yellow with iodine
 Hydrolysis yields fructose
 Sources include onions, garlic, jerusalem artichokes
 Used as diagnostic agent for the evaluation of GFR-
glomerular filtration rate (renal function test)
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Jerusalem artichokes

46. Dextrans
 Products of the reactions of glucose.
 Contains a (1,4), a (1,6) and a (1,3) linkages
 Mw: 40,000; 70,000; 75,000
 Used as plasma extenders (treatment of shock)
 Also used as molecular sieves to separate proteins
and other large molecules (gel filtration
chromatography)
 Components of dental plaques
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47. Dextrins
 Produced by the partial hydrolysis of starch along
with maltose and glucose
 Dextrins are often referred to as either
amylodextrins, erythrodextrins or achrodextrins
 Used as mucilages (glues)
 Also used in infant formulas (prevent the curdling
of milk in baby’s stomach)
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48. Chitin
 Chitin is the second most abundant
carbohydrate polymer
 Present in the cell wall of fungi and in the
exoskeletons of insects and spiders.
 Chitin is used commercially in coatings
(extends the shelf life of fruits and meats)
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49. Carbohydrates
Heteropolysaccharides
(Hetroglycans)
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Glycosaminoglycans
(GAGs)
GLYCOCONJUGATES
• Proteoglycans
• Glycoproteins
• Glycolipids
Mucilages

50. Glycosaminoglycans
 These are mucopolysaccharides (MPS)
 Contains amino sugars and acid sugars
 With proteins, known as Proteoglycans.
 Present in bone, elastin, collagens
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Makes ground substance, acts as lubricating,
cushioning & structure formations these are:
Hyaluronic Acid Keratan sulfate
Chondroitin Sulfate Dermatan sulfate
Heparan sulfate Heparin

51. Summary of GAGs
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52. Glycosaminoglycans (GAGS)
Involved in a variety of extracellular functions; chondroitin
is found in tendons, cartilage and other connective tissues
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53. Glycosaminoglycans
A characteristic of glycosaminoglycans is the presence
of acidic functionalities (carboxylate and/or sulfates)
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54. Mucopolysaccharidoses
MPS are hereditary diseases caused by defiency of lysosomal
hydrolasis. MPS are accumulated in skeletol & EC matrix making
them defective. Mental retardation can occur as well
 Hurler syndrome
 Hunter syndrome
 Sanfilippo syndrome
 Sly syndrome
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55. Glycoproteins
 These are mucoproteins.
 CHO are less as compared to proteoglycans.
 Composed of protein & oligosaccharides.
 Occurs in fluids and tissues and cell membranes.
 Synthesized in ER & Golgi and degraded by lysosomal acid hydrolases
 Accumulation can cause storage diseases
& I-Cell Disease in which mannose is not phosphorylated
Functions
 Cell surface antigenicity
 Cell surface recognition
 Compontents of extracellular matrix and mucins
 Examples are globurlar proteins in plasma
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56. Glycoproteins with functions
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57. Comparison
Proteoglycans-GAGs Glycoproteins
Heterploysaccharides with proteins Hetero-oligosaccharides with
proteins
Long chains Short chains
Unbranched Branched
Negatively charged May or may not be
Repeating disaccharide units No repeating disaccharides
Support the tissues mediate cell-cell
signaling
Cell surface recognition.
Cause adhesions Cell surface antigenicity
Viscous & lubricating Component of E.C. matrix
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58. GLYCOLIPIDS
1. Oligosaccharides covalently bind with
lipids, form outer surface of plasma
membrane.
2. Common example is of gangliosides
bind with oligosaccharides containing
sialic acid and monosaccharides.
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59. Mucilages
Present mainly in plants
Form gels and have adhesive properties
Maybe used in
Pharmaceuticals
Culture media
Usually not digestible.
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Acts as a laxative, increases intestinal peristalsis.
Important examples are:
Agar
Vegetable Gums
Pectins
Hemicellulose

60. Pectins
 pectins are heteropolysaccharides found
in the pulp of fruits (citrus, apples)
 on hydrolysis pectins yield galacturonic
acid, galactose, arabinose, methanol
and acetic acid
 pectins are composed of galactose &
arabinose
 used as gelling agents (to make jellies)
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62. Thank You
Good Luck 62