# Poly saccharides composed of large number of monosaccharide units.
# Suffix '---an' is added in their names and they are known as glycans.
# Pentose polysaccharides are called pentosans for e.g.
araban (from L- arabinose), xylan (from D-xylose), all these found in cell wall.
# Hexose polysaccharides are called "hexans". for e.g. mannan (from mannose) cellulose, starch etc.
# Polysaccharides are insoluble in water and do not taste sweet.
# All polysaccharide are non-reducing
# Although polysaccharide is non reducing but in a polysaccharide chain one end is reducing and another end
is non reducing.
# According to function, they are classified as nutritive and structural.
On structural basis polysaccharides are of two types.
(I) Homopolysaccharides :-
Composed of same monomers. Biologically important homopolysaccharides are as follows:
(a) Cellulose :- Linear polymer of `beta-D`-glucose units (6000 to 10,000). It has `beta` 1'-4" linkage. Pa1iial
digestion yields a cellobiose units (Disaccharide).
Cellulose is main component of plant cell wall. In wood, cellulose is 509{1 and in cotton, it is 909;().
# Most abundant organic molecule on earth.
# In urochordates animals their occur cellulose like material and it is called "Tunicine" lt is also called
Animal cellulose.
# It is also used to form Rayon fibre (Artificial silk).
# Paper made from plant pulp is cellulose.
(b) Starch- It is main stored food in plants. Starch is polymer of `alpha -D`-glucose units. Starch consits of two
types of chains.
(i) Amylose :- 250-300 glucose units are arran~~ed in an unbranched chain by `alpha` 1 '-4" linkage
(ii) Amylopectin :-A branched chain molecule. Approximately 30 glucose units are linked by `alpha-`
1',4" and `alpha` 1', 6" linkage.
`->` Amylose gives blue colour with iodine.
`->` Amylopectin gives red colour with iodine.
`->` Starch present in potato contains `20%` amylose and `80%` amylopectin.
`->` Starch form helical structure so starch can hold `I_2` molecules in the helical portion so starch -`I_2` is
blue- violet in colour. While cululose have linear structure so it cannot hold 12 and don't give Iodine test.
(c) Glycogen :-Storage form of carbohydrate in animals, storage region of glycogen is liver and muscles.
Storage of glycogen liver> muscle. Glycogen is also called as animal starch. Glycogen is highly branched
polymer of `alpha-D`-glucose.
`->` Glycogen is formed by the 1 ',4" bond linkage at long chain and 1',6" bond linkage at branching point.
`->` Glycogen gives red colour with iodine.
`->` Glycogen is store food of fungi.
(d) Chitin:- Linear polymer of N-acetyl- D-glucosamine with `beta`-1 ', 4"--linkage.
`->` N-acetyl D-glucosarnine is an amino acyl `(-NH-CO-CH_(3))` derivative of `beta-D`-glucose.
`->` Chitin is an important component of exoskeleton of Arthropods and cell walls of fungi.
`->` Second most abundant organic molecule on earl h.
`->` It is also called Fungal cellulose.
(e) Inulin:- Linear polymer of fructose units linked with `beta` 1',2" bonds. Inulin is found in roots of Dahalia
and Artichoke. It is water soluble polysaccharide and if is used to know the glomerular filteration rate.
`->` It is smallest storage polysaccharide.
(f) Dextrin- Dextrin is an intermediate substance in the digestion of glycogen and starch. By hydrolysis of
dextrin, glucose and maltose are formed. It also occurs as stored food in yeast and bacteria.
# Poly saccharides composed of large number of monosaccharide units.
# Suffix '---an' is added in their names and they are known as glycans.
# Pentose polysaccharides are called pentosans for e.g.
araban (from L- arabinose), xylan (from D-xylose), all these found in cell wall.
# Hexose polysaccharides are called "hexans". for e.g. mannan (from mannose) cellulose, starch etc.
# Polysaccharides are insoluble in water and do not taste sweet.
# All polysaccharide are non-reducing
# Although polysaccharide is non reducing but in a polysaccharide chain one end is reducing and another end
is non reducing.
# According to function, they are classified as nutritive and structural.
On structural basis polysaccharides are of two types.
(I) Homopolysaccharides :-
Composed of same monomers. Biologically important homopolysaccharides are as follows:
(a) Cellulose :- Linear polymer of `beta-D`-glucose units (6000 to 10,000). It has `beta` 1'-4" linkage. Pa1iial
digestion yields a cellobiose units (Disaccharide).
Cellulose is main component of plant cell wall. In wood, cellulose is 509{1 and in cotton, it is 909;().
# Most abundant organic molecule on earth.
# In urochordates animals their occur cellulose like material and it is called "Tunicine" lt is also called
Animal cellulose.
# It is also used to form Rayon fibre (Artificial silk).
# Paper made from plant pulp is cellulose.
(b) Starch- It is main stored food in plants. Starch is polymer of `alpha -D`-glucose units. Starch consits of two
types of chains.
(i) Amylose :- 250-300 glucose units are arran~~ed in an unbranched chain by `alpha` 1 '-4" linkage
(ii) Amylopectin :-A branched chain molecule. Approximately 30 glucose units are linked by `alpha-`
1',4" and `alpha` 1', 6" linkage.
`->` Amylose gives blue colour with iodine.
`->` Amylopectin gives red colour with iodine.
`->` Starch present in potato contains `20%` amylose and `80%` amylopectin.
`->` Starch form helical structure so starch can hold `I_2` molecules in the helical portion so starch -`I_2` is
blue- violet in colour. While cululose have linear structure so it cannot hold 12 and don't give Iodine test.
(c) Glycogen :-Storage form of carbohydrate in animals, storage region of glycogen is liver and muscles.
Storage of glycogen liver> muscle. Glycogen is also called as animal starch. Glycogen is highly branched
polymer of `alpha-D`-glucose.
`->` Glycogen is formed by the 1 ',4" bond linkage at long chain and 1',6" bond linkage at branching point.
`->` Glycogen gives red colour with iodine.
`->` Glycogen is store food of fungi.
(d) Chitin:- Linear polymer of N-acetyl- D-glucosamine with `beta`-1 ', 4"--linkage.
`->` N-acetyl D-glucosarnine is an amino acyl `(-NH-CO-CH_(3))` derivative of `beta-D`-glucose.
`->` Chitin is an important component of exoskeleton of Arthropods and cell walls of fungi.
`->` Second most abundant organic molecule on earl h.
`->` It is also called Fungal cellulose.
(e) Inulin:- Linear polymer of fructose units linked with `beta` 1',2" bonds. Inulin is found in roots of Dahalia
and Artichoke. It is water soluble polysaccharide and if is used to know the glomerular filteration rate.
`->` It is smallest storage polysaccharide.
(f) Dextrin- Dextrin is an intermediate substance in the digestion of glycogen and starch. By hydrolysis of
dextrin, glucose and maltose are formed. It also occurs as stored food in yeast and bacteria.