Carbohydrates are your body's main source of energy: They help fuel your brain, kidneys, heart muscles, and central nervous system. For instance, fiber is a carbohydrate that aids in digestion, helps you feel full, and keeps blood cholesterol levels in check.

1. CARBOHYDRATES: CLASSIFICATION,
DIGESTION & ABSORPTION
Submitted by –
Virendra Kumar
MFSc
RPCAU, Pusa, Bihar

2. CARBOHYDRATE
 Carbohydrates are probably the most abundant and widespread organic
substances in nature, and they are essential constituents of all living things.
 General names for carbohydrates include sugars, starches, saccharides, and
polysaccharides.
 The term saccharide is derived from the Latin word " sacchararum" from the
sweet taste of sugars.
 Carbohydrate Composed mainly of molecules
containing atoms of carbon (C), hydrogen (H), and oxygen (O) and to have the
general formula C6H12O6.
 Carbohydrates serve as energy sources and as essential structural components in
organisms; in addition, part of the structure of nucleic acids, which contain
genetic information, consists of carbohydrate.

3. CLASSIFICATION OF CARBOHYDRATES
1) Monosaccharides
2) Disaccharides
3) Oligosaccharides
4) Polysaccharides

4. Monosaccharides
 Includes 1 sugar molecule.
 Simple sugars & simplest form of sugar.
 Most basic unit of carbohydrates.
 Monosaccharides are reducing sugars.
 Sweet taste sugar.
Eg :-
1) Glucose (hexose)
2) Fructose (hexose)
3) Galactose (hexose)
4) Ribose (pentose)
5) Erythrose (tetrose)
6) Glyceraldehyde (triose)

5. Disaccharides
• Made up of 2 monosaccharides joined together by a
condensation reaction.
• A glycosidic bond is formed between 2 monosaccharides.
• Sucrose is a non- reducing sugar
• Eg:-
1) Maltose (Glucose + Glucose) :Malt sugar
2) Sucrose (Glucose + Fructose) : Transport sugar
3) Lactose (Glucose + Galactose) :Sugar found in milk

6. Oligosaccharides
• Formed by containing 3-10 molecules of
monosaccharides/ simple sugars.
• Eg:-
1) Raffinose
2) Stachyos
3) Glycolipids

7. Polysaccharides
• Formed by combining many monosaccharide molecules (more
than 2) by condensation reactions.
• Monosaccharide molecules containing 11 or more than 11
Monosaccharides are true polysaccharides.
• Polysaccharides do not taste sweet.
• Do not dissolve in water.
Eg:-
1) Starch
2) Glycogen
3) Cellulose

8. Function of Carbohydrates
 Energy supply for body function.
 Main source of energy in animal body.
 Essential for oxidation of fats.
 Add flavour to diet.
 Structural components of cell membrane.
 Carbohydrates form part of the structural framework of
DNA and RNA molecules.
 Part of connective tissues, some hormones and enzymes.
 Carbohydrate storage in the form of glycogen, provides a
short-term energy reserve.

9. Digestion Of Carbohydrates
• Digestion of Carbohydrates Begins in the Mouth and
Stomach.
• When food is chewed, it is mixed with saliva, which
contains the digestive enzyme ptyalin (an α-amylase)
secreted mainly by the parotid glands.
• This enzyme hydrolyzes starch into the disaccharide
maltose and other small polymers of glucose that contain
three to nine glucose molecules.

10. • However, the food remains in the mouth only a
short time, so probably not more than 5 percent
of all the starches will have become hydrolyzed by
the time the food is swallowed.
• Activity of the salivary amylase is then blocked by
acid of the gastric secretions because the amylase
is essentially inactive as an enzyme once the pH of
as an enzyme falls below about 4.0

11. Digestion at the brush border of intestine
• The intestine cannot absorb
these products of amylase
digestion of starch, and thus
further digestion is required
to produce monosaccharides
• The human small intestine
has enzymes on brush
border
oligosaccharidases:lactase,
glucoamylaseand sucrase-
isomaltase.