The document discusses carbohydrates as polyhydroxy aldehydes, ketones, or their derivatives, classified into monosaccharides, disaccharides, oligosaccharides, and polysaccharides based on their size and structure. It details their functions as energy sources, food reserves, and structural components in animals and plants, along with specific examples and their roles in various biological processes. It emphasizes the importance of carbohydrates in nutrition and their classification into soluble and insoluble types depending on digestibility.

1. PRESENTATION
TITLE : CARBOHYDRATES
Dr. Rahul
Kumar Dangi

2. CARBOHYDRATES
 • CHO : CHO may be defined as polyhydroxy aldehyde, ketones or acids and
their derivatives.
 • CHO : Based on their digestibility & solubility , the CHO divided in to two
parts
1. – Soluble CHO / easily digest - NFE ( Sugar, Starch, Hemicelluloses)
2. – Insoluble CHO / less digest in non ruminant but digestible in ruminant
(Crude fibre, cellulose, Ligniin)
 • Carbohydrates are neutral chemical compounds containing the elements
carbon, hydrogen & oxygen & have empirical formula (CH2O)n where n is
three or more.
DR. RAHUL DANGI

3. FUNCTION OF CARBOHYDRATES
 • Important source of energy
 • As important food reserves
 • In the storage of Liver and muscle of the liver Glycogen
Liver glycogen muscle glycogen
 • In the seed →as starch
 • Transfer of genetic characteristic of the cell
DR. RAHUL DANGI

4. • Carbohydrates make the matrix of
connective tissue eg. Hyaluronic acid
• They make structural part of cartilage, bone
and tendons eg. Chondroitin sulphate
• Oxidation of protein & fat as they are
important component.
• Essential component of milk as lactose.
• It helpful in absorption of calcium &
phosphorus in younger animals.
• They help in peristaltic movement of food.
DR. RAHUL DANGI

5. CLASSIFICATION OF CARBOHYDRATES:
 In nutrition, carbohydrates are classied into five groups:
 • (1) monosaccharides (also known as simple sugars);
 • (2) disaccharides (containing 2 monosaccharide units);
 • (3) oligosaccharides (containing 3–10 monosaccharide units);
 • (4) polysaccharides (containing more than 10 monosaccharide units); and
 • (5) conjugated carbohydrates. covalently bound to lipids or proteins to form glycolipids or
glycoproteins, respectively. Polysaccharides are subdivided into
I. – Homopolysaccharides (containing only one type of monosaccharide) and
II. – Heteropolysaccharides (containing more than one type of monosaccharide).
DR. RAHUL DANGI

6. CLASSIFICATION OF CARBOHYDRATES
 • Monosaccharides –
i. Trioses (C3H6O3) Glyceraldehyde and dihydroxyacetone –
ii. Tetroses (C4H8O4) Erythrose –
iii. Pentoses (C5H10O5) Aarabinase, xylose, xylulose, ribose, ribulose, and 5-deoxyribose –
iv. Hexoses (C6H12O6) Glucose, fructose, galactose, and mannose –
v. Heptoses (C7H14O7) Sedoheptulose, mannoheptulose (in avocados), and -glycero--manno-
heptose
 • Disaccharides Sucrose (-α-glucose and -α-fructose), lactose (milk sugar; -α-glucose and -α-
galactose), maltose, isomaltose, cellobiose, α,α-trehalose, α,β-trehalose, and β,β-trehalose)
 • Oligosaccharides
I. – Trisaccharides, Rafnose, kestose, maltotriose (three units of glucose), planteose, and
melezitose (in sweet exudates of many trees and in insects), and panose (synthesized by
microbes) DR. RAHUL DANGI

7. POLYSACCHARIDES
 – Homoglycans
I. • Pentosans (C5H8O4)n, for example, arabans and xylans
II. • Hexosans (C6H12O6)n, for example, starch, cellulose, mannans, levans, and glycogen
 – Heteroglycans Hemicelluloses, pectins, exudate gums, seaweed polysaccharides (algin, carrageenans,
agar, aminopolysaccharides [e.g., chondroitin and hyaluronic acid], and sulfated polysaccharides [e.g.,
chondroitin sulfate])
 • Conjugated carbohydrates
i. – Glycolipids: Glyceroglycolipids and sphingolipids
ii. – Glycoproteins : Mucins, immunoglobulins, and membrane-bound hormone receptors
DR. RAHUL DANGI

8. Monosaccharides :-
 • Monosaccharides or simple sugars are those that can not be
hydrolysed into simpler form’ seldom found free in nature.
 • They constitute the building block of more complex carbohydrate
molecules. • Because of the presence of an active aldehyde or ketone
grouping, the monosaccharides act as reducing substances.
 • They may be subdivided into trioses, pentoses or hexoses, depending
upon the no. of carbon atom they posses; as aldoses or ketoses,
depending upon whether the aldehyde or ketone group is present.
 • All monosaccharides are highly soluble in water.
 • Monosaccharides commonly present in plant cell walls are hexoses (-
glucose, -galactose, and -mannose), pentoses (- arabinose and -
xylose), 6-deoxyhexoses (-rhamnose and - fucose), and uronic acids
(glucuronic and galacturonic or their 4-o-methyl ethers). DR. RAHUL DANGI

9. Pentoses: (C5H10O5 )
 • The most important members of this group are the
aldoses L-arabinose, D-xylose & Dribose, & the ketoses D-
xylulose & D-ribulose.
 • L-arabinose occurs as pentosans in arabinans. It is
component of hemicelluloses & it is found in silage as a
result of their hydrolysis.
 • D-xylose also occurs as pentosans in xylans.
 • D-ribose is present in all living cells as a component of
ribonucleic acid & it also a component of several vitamins
& coenzymes.
DR. RAHUL DANGI

10. Hexoses: (C6H12O6 )
 • Glucose & fructose are the most important naturally occurring hexose
sugars; while mannose & galactose occur in plants in a polymerised form
as mannans & galactans.
 1)D-glucose:
 • Also k/as grape sugar or dextrose or blood sugar.
 • Exists in free state as well as combined state.
 •In the pure state ,it is white crystalline solid & like all sugars is soluble in
water.
 • It occurs free in plants , fuits ,honey, blood ,lymph & CSF. • The majority
of carbohydrates taken in by the body are eventually converted to
glucose in a series of metabolic pathway.
 • Glucose is dextrorotatory.
 • Glucose is only 75% as sweet as sucrose i.e. table sugar but it has the
same caloric value. DR. RAHUL DANGI

11. • 2)D-fructose: • Fruit sugar or laevulose. • Fructose is the only
naturally occurring ketohexose. • It is the sweetest sugar & is
found together with glucose & sucrose, in sweeter fruits &
honey. • Green leafy crops usually contain appreciable
amounts of this sugar both free & polymerised form. • The
free state is a white crystalline solid . 23
• 3)D-galactose: • It doesn't occur free in nature except as a
breakdown product during fermentation. • It is present as a
constituent of the disaccharide lactose, which occurs in milk.
• 4)D-mannose: • It doesn't occur free in nature but exists in
polymerised form as mannans & also a component of
glycoproteins. • Mannans are found widely distributed yeasts ,
DR. RAHUL DANGI

12. OLIGOSACCHARIDES:
A)Disaccharides
B)Trisaccharides
C) Tetrasaccharides
 A)Disaccharides: These are compound sugars composed of two
monosaccharides, which linked with glycosidic bond • Sucrose –
table sugar • Lactose – milk sugar • Maltose – repeating unit of
starch • Cellobiose – repeating unit of cellulose
DR. RAHUL DANGI

13. Disaccharides
• Sucrose = Glucose + Fructose
• Lactose = Glucose + Galactose
• Maltose = Glucose + Glucose with alpha
bond
• Cellobiose = Glucose + Glucose beta bond
DR. RAHUL DANGI

14.  1)Sucrose:
• Also known as beet sugar or cane sugar or table sugar or simply as sugar. • It is
probably the largest selling pure organic compound in the world . • Sucrose is
formed from one molecule of α-Dglucose & one molecule of β-D-fructose with
an α1,2 glycosidic bond linked together through an oxygen bridge between the
respective carbon atoms 1 & 2. • Sucrose has no active reducing group. • It is the
most ubiquitous & abundantly occurring disaccharide in plants, where it is the
main transport of carbon.
 2) Lactose:
• Also c/as milk sugar , is a product of mammary gland. • Cow’s milk contain 43-
48 g/kg. • It is not as soluble as & is less sweet , imparting only a faint sweet
taste to milk. • Lactose is formed from one molecule of α-D-glucose linked to
one of β-D-galactose in a β-1,4 galactosyl bond & has one active reducing
group. • It readily undergoes fermentation by a number of organisms , including
Streptococcus lactis. • S. lactis is responsible for souring of milk by converting
the lactose into lactic acid.
DR. RAHUL DANGI

15.  3)Maltose: • Also called malt sugar , is produced during the hydrolysis of
starch & glycogen by dilute acids or enzymes. • It is produced from
starch during the germination of barley by the action of enzyme
amylase. • Maltose is water soluble & not as sweet as sucrose. •
Structurally, it consists of two α-D-glucose residues linked in the α-1,4
positions & it has one active reducing group.
 4) Cellobiose • Cellobiose (the fundamental repeating unit of cellulose)
is a reducing sugar and consists of two β-D-glucose molecules linked by
the β-1,4 glycosidic bond. • Cellobiose can be synthesized from two
units of β-D-glucose or obtained by enzymatic or acidic hydrolysis of
cellulose and cellulose-rich materials (e.g., cotton and paper). • The
difference in the conguration of the glycosidic link between maltose (α-
1,4 bond) and cellobiose (the β-1,4 bond) is responsible for their
DR. RAHUL DANGI

16. OLIGOSACCHARIDES
 • Oligosaccharides consist of 3–10 units of
monosaccharides, which are linked via glycosidic
bonds.
 • Bacteria in the digestive tract of animals possess
enzymes to hydrolyze all oligosaccharides with α-1,4
or β-1,4 linkages.
DR. RAHUL DANGI

17. B)Trisaccharides:
1)Raffinose &
2)Kestose are two important
naturally occurring trisaccharides.
c)Tetrasaccharides ;These are made
up of four monosaccharide
residues. e.g. stachyose.
DR. RAHUL DANGI

18. POLYSACCHARIDES:
❶Homoglycans
❷Heteroglycans
DR. RAHUL DANGI

19. • ❶Homoglycans:
Homopolysaccharides (homoglycans) are polysaccharides consisting of a
single type of many monosaccharide molecules joined together through
glycosidic linkages.
• Depending on the monosugar, a homopolysaccharide may be called
I. glucan (consisting of -glucose);
II. fructan (consisting of fructose);
III. galactan (consisting of galactose);
IV. arabinan (consisting of arabinose); or
V. xylan (consisting of xylose).
• Plant-source homopolysaccharides include starch, cellulose, levans,
galactans, and β--glucans.
Glycogen serves to store glucose and energy in animals
• Animal cells can hydrolyze homopolysaccharides with an α-1,4 linkage but
not those with a β-1,4 linkage. However, cellulose, levans, galactans, and β--
glucans can be extensively degraded by enzymes released from bacteria
present in the rumen of ruminants and in the large intestine of all animals
DR. RAHUL DANGI

20. A)Arabinans & xylans : – These are polymers of
arabinose & xylose, respectively.
B)Glucans: 1) Starch 2) Dextrins 3) Glycogen 4)
Cellulose
5) Callose
DR. RAHUL DANGI

21. 1)Starch :
• It is present in many plants as a reserve carbohydrate . It is most abundant in seeds , fruits , tubers & roots . • Starches
naturally occur in the form of granules . • Starches differ in their chemical composition, except in rare instances, mixtures of
structurally different polysaccharides, amylose (straight chain polymer) & amylopectin (branched chain polymer). • The ratio of
amylose to amylopectin varies with the sources of starch, but it is usually 1:3 (g/g) • Amylose is mainly long linear in structure,
the α-D-glucose residues being linked between carbon 1 atom of one molecule & carbon atom 4 of the adjacent molecule. It
has no branch 38 1)Starch : • Amylopectin has a small chain brush like structure containing primarily α-(1→4) linkages in the
main chain and an appreciable number of α(1→6) linkages in branch chain. – Starch is made of repeating units of the
disaccharide MALTOSE – so it is really all: GLUCOSE • Starch granule are insoluble in cold water , but when a suspension in water
is heated, the granules swell & eventually gelatinise. • Animals consume large quantities of starch in cereal grains, cereal
byproducts and tubers.
• On the basis of the rates of their in vitro enzymatic digestion, there are three types of starch: • (1) rapidly digested starch (with
high amylopectin content and high digestibility containing 100% amylopectin and 0% amylose), freshly cooked starch, and
white bread; • (2) slowly digested starch (with a certain weight ratio of amylose to amylopectin of, e.g., 45:55 [more amylopectin
than amylose] and low digestibility), such as starch in most raw cereals (dent corn varieties, barley, wheat, and rice), whose
semicrystalline structure renders it less accessible to digestive enzymes; and • (3) resistant starch (with high-amylose content
and limited digestibility), such as high-amylose corn, high-amylose wheat, legumes, and bananas
• In its natural state, tuber and grain starch (e.g., in potatoes) exist in a water-insoluble granular form, which resists digestion in
the small intestine of nonruminants . Such starch-containing foods must be cooked before they can be more effciently utilized
by chickens and pigs. • The cooking of foods markedly aids in their digestion by animals through breaking down (gelatinizing)
and solubilizing starch granules.
DR. RAHUL DANGI

22. 2)GLYCOGEN:
 • This term is used to describe a group of highly branched polysaccharides isolated from animals or
microorganisms. • Glycogen occur in liver (1.5- 4%) , muscles (0.5-1 %) &other tissues. • They are
analogous to amylopectins in structure & have been referred as ‘animal starches’ . • Glycogen is the
main carbohydrate storage product in animal body & plays an essential role in energy metabolism . •
Glycogen can be broken down into it D-glucose by acid hydrolysis or by means of some enzymes that
attack starch. • In animals, the enzyme phosphorylase catalyses the breakdown of glycogen into
phosphate esters of glucose. 42 3)Cellulose:
 ♣ It is the most abundant single polymer in the plant kingdom , forming the fundamental structure of
cell walls.
 ♣ Cotton fiber & filter paper are almost entirely cellulose.
 ♣ Pure cellulose is a homoglycan of high molecular weight in which the repeating unit is cellobiose. Here
the D-glucose residues are β -1,4-linked
 ♣ In plants , cellulose chains are formed in an ordered manner to produce compact aggregates
(microfibrils ) which are held together by both inter- & intra- molecular hydrogen bonding.
DR. RAHUL DANGI

23. 3)CELLULOSE:
 ♣ It is the most abundant single polymer in the plant kingdom , forming
the fundamental structure of cell walls.
 ♣ Cotton fiber & filter paper are almost entirely cellulose.
 ♣ Pure cellulose is a homoglycan of high molecular weight in which the
repeating unit is cellobiose. Here the D-glucose residues are β -1,4-
linked
 ♣ In plants , cellulose chains are formed in an ordered manner to
produce compact aggregates (microfibrils ) which are held together by
both inter- & intra- molecular hydrogen bonding.
DR. RAHUL DANGI

24. THE DIFFERENCE BETWEEN STARCH AND
CELLULOSE
• Starch is glucose connected with alpha bonds
• Cellulose is glucose connected with beta bonds
• Animals do NOT make the enzyme that digests
beta bonds.
• Only bacteria make cellulase
DR. RAHUL DANGI

25. THANK YOU
,
DR. RAHUL DANGI