homopolysaccharides are only discussed

1. POLY SACCHARIDESHOMO POLY SACCHARIDES
HETRO POLY SACCHARIDES

2. • Polymerized products ( medium / high molecular
weight) of mono saccharides.
• Differ from each other in respect of
1. Their recurring mono saccharide units
2. Length of their chains
3. Type of linkage
4. Degree of branching

3. HOMO POLY SACCHARIDES
• Have only one type of mono saccharide units
EXAMPLES
I. Starch
II. Glycogen
III. Cellulose
IV. Chitin
V. Dextrin
VI. Dextrans
VII. Inulin

4. HETRO POLY SACCHARIDES
• Glycosaminoglycans
• Glyco-conjugates
I. Proeoglycans
II. Glycoproteins
III. Glycolipids

5. STARCH
• Homo polymer of Glucose , forms an α- glycosidic
chain. (glucosan / glucan chain )
• SOURCES
• Cereals , potatoes ,legumes & tubers .
• Main dietary source of higher animals.
• Stored fuel in plant, animal & bacterial cells.

6. • COMPOSITION
• Two types of poly saccharide units
I. Amylose 13-20% (non branching helical structure.)
II. Amylopectin 80-85% (branched chain )
composed of 24-30 glucose residues united by α 1-4
linkage in chains & α 1-6 linkage at branch points.

10. • Amylose
• Soluble part of starch ,shows 1-4 linkage .
• Amylopectin
• Insoluble part ,forms Gel , shows both
• α 1-4 linkages
• α 1-6 linkages at branch points
• Branch points occur at every 24-30 residues .
• Starch is a non reducing sugar ,does not form Osazone
crystals .

11. HYDROLYSIS OF STARCH
• Acids completely hydrolyze starch into glucose
,through different stages .
I. Starch (insoluble in water) gives blue color with
Iodine.
II. Hydrolysis for a short time produces
AMYLODEXTRIN which gives violet color with
Iodine.
III. Further hydrolysis gives ERYTHRODEXTRIN which
gives Red color with Iodine.
IV. More hydrolysis yields ACHRODEXTRINS, MALTOSE
&GLUCOSE .

12. ACTION OF AMYLASES
• α- Amylase acts on the α 1-4 glycosidic linkages &
forms
α Dextrins & α – Maltose
• β- Amylase splits Starch into β-Maltose .
• In humans salivary Amylase hydrolyzes 1-4 linkages
randomly ,while Pancreatic Amylase converts starch
into Maltose, Maltotriose & α -Limit Dextrins .

14. • LIMIT DEXTRINS
• End product of α- Amylase activity .
• Composed of branched (4-9)
Glucose polymers.
• End –products of starch hydrolysis .

15. GLYCEMIC INDEX
• The measure of digestibility of a starchy food based
on the extent to which it raises the blood
concentration of Glucose compared with an
equivalent amount of Glucose or a reference food
i.e. white Bread.

17. • Some carbohydrate containing foods produce rapid rise
followed by steep fall in the blood glucose level or vice versa
.
• Glycemic index of
1. Glucose /Galactose 1
2. Fructose / Sucrose < 1
3. Starch 0-1
4. Non starch poly saccharides 0

18. • Foods with low glycemic index are beneficial
as,
I. They create sense of satiety
II. Help in limiting caloric intake
III. Cause less fluctuation in Insulin secretion.

19. GLYCOGEN
• Animal’s Starch (storage poly saccharide)
• Highly branched structure
• 12-14 α-Glucopyranosyl residues in 1-4 glycosidic
linkage with 1-6 linkage at branch points.
• Stored in Liver & Muscles .
• Liver utilizes Glycogen to maintain blood Glucose
level
• Muscles use Glycogen to provide energy for
muscular contraction.

22. • Synthesized in liver during well fed state .
• Present in Hepatocytes as large granules .
• Inner most core of Glycogen contains primer GLYCOGENIN .
• Hydrolytic Enzymes work simultaneously at various
branches to convert Glycogen into Glucose.

23. CELLULOSE
• Fibrous , water insoluble & tough supporting tissue of
plants.
• Major constituent of plant cell wall.
• comprises of β D –Glucopyranose units linked by β(1-4)
linkage to form long straight chains strengthened by
cross linked H- bonds .
• Non branching structure .
• Hydrolyzed by CELLOBIASE (β Amylase).
• Non digestible part of food
• Used as dietary fiber.

26. DIETYARY FIBER
• BENEFITS
I. Gives bulk to food .
II. Delays gastric emptying & gives sense of satiety
III. Absorbs water & increases gastric motility .
IV. Reduces exposure of gut to the carcinogens .
V. prevents constipation & hemorrhoid formation.
VI. Major source of energy for ruminants .
DAILY REQUIREMENT
Males 38 grams
Females 25 grams

27. HEMI CELLULOSE
• Mixture of neutral Hetero glycans , linking poly
saccharide of cellulose units in plants.
• High molecular weight ,resembles cellulose .
• Soluble ,can be easily decomposed .
• On hydrolysis yields Aldo Hexoses ,pentoses,
uronic acids & xylose polymers.

28. DEXTRANS
• Bacterial & yeast Poly saccharides, made up of Glucose
residues with α 1-6 linkages & 1-3 bonds at branch
points.
• Synthetic Dextrans are used in
I. Fractional chromatography.
II. As food components.
III. Plasma expander for the treatment of Hypo- volemic
shock.
IV. Dental plaque is rich in Dextrans.

29. INULIN
• Fructose polymer with β 1-2 linkage.
• Water soluble , not hydrolyzed by intestinal
bacteria.
SOURCES
• Tubers ,Dahlias ,Dandelions, Artichokes .
USES
1. As a starch substitute in dietary products for
Diabetics.
2. To determine GFR .

30. CHITIN
• N- Acetyl Glutamine units joined by β 1-4 linkage .
• Structural component of exoskeleton of insects,
crustaceans & cell wall of fungi .

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