importance of polysaccharides in the body , glycemic index ,different homopolysaccharides

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

4.  Glycosaminoglycans
 Glyco-conjugates
I. Proeoglycans
II. Glycoproteins
III. Glycolipids

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