Carbohydrates are polyhydroxy aldehydes or ketones that yield monosaccharides like glucose, fructose, and galactose upon hydrolysis. They serve important functions like energy storage, structural support, and participation in cellular processes. Carbohydrates are classified as monosaccharides, oligosaccharides, or polysaccharides depending on the number of monosaccharide units present. Monosaccharides are the simplest form and include hexoses like glucose. Oligosaccharides contain 2-10 monomer units and include disaccharides like sucrose. Polysaccharides are long chains with high molecular weights and function as storage molecules in plants and animals.

1. CARBOHYDRATES

2. Definition
Chemically Carbohydrates can be defined as
polyhydroxy-aldehydes or Ketones or
compounds which produce them on hydrolysis.
• The word Carbohydrates Literally means ‘hydrates of carbon’
(carbon with attached water i.e. (C.H2O)n.
• Most abundant organic molecule in nature.
• When n=3 it satisfies the definition of hydrates of carbon.
 Carbohydrates are also known as SUGARS but the term ‘sugar’ is
applied only for those carbohydrates that are soluble in water and
sweet in taste.

3. Functions
The most abundant dietary source of energy (4cal/g) for all
organism.
Precursors for many organic compounds (fats, amino acids etc).
Carbohydrates ( as glycoprotein and glycolipids) participate in the
structure of cell membranes and cellular functions such as cell
growth etc.

4. Functions
Structural components of many organisms like the fiber (cellulose)
of plants, exoskeleton of some insects and the cell wall of
microorganisms.
Also serve as the storage form of energy(glycogen) to meet the
immediate energy demands of the body.
They are utilized as raw materials for several industries e.g. paper,
plastic, textile alcohol etc.

5. Classification
Carbohydrates are often referred to as saccharides .
Broadly classified into 3 groups.
1. Monosaccharides
2. Oligosaccharides
3. Polysaccharides

6. Monosaccharides
 Mono = 1, Sacchride =sugar
 Simplest form of carbohydrates and are referred as
simple sugars.
 They cannot be further hydrolyzed.
 Sweet in Taste.
 Soluble in water.
 Have general formula Cn(H2O)n.
• Examples:
o Glucose
o Fructose
o Galactose

7. Classification of Monosacchrides
• Monosacchrides can be classified on
the basis of:
1. the functional groups
2. the number of carbon atoms.
• on the basis of functional groups they are classified
as
1. Aldoses: Aldehyde as functional group
2. Ketoses: ketone as functional group

8. Monosaccharides
• On the basis of number of carbon atoms they are classified as
1. Trioses: 3 carbon
2. Tetroses: 4 carbon
3. Pentoses: 5 carbon
4. Hexoses: 6 carbon
5. Heptoses: 7 carbon
These terms are used along with functional groups while naming
monosaccharides.
e.g. Glucose is Aldohexose and Fructose is Ketohexose.

9. Oligosaccharides
 Oligo means “few”
 Saccharides means “sugar”
 Contains 2-10 monosaccharide molecules which are liberated on
hydrolysis.
 Properties:
 Less sweet in taste.
 Less soluble in water

10. Types of Oligosachharides
 Based on the number of monosaccharides units
present they are subdivided as.
1. Disaccharides :
• On hydrolysis produce 2 molecules of the same or
different monosaccharide.
I. Maltose Glucose + Glucose
II. Sucrose Glucose + Fructose
III. Lactose Glucose + Galactose

11. Types of Oligosaccharides
2. Trisaccharides :
• Contains 3 monosaccharide units .
Raffinose Fructose+Galactose+Glucose
3. Tetrasaccharides :
• Contains 4 monosaccharide units.
Stachyose 2(Galactose)+Glucose+Fructose
4. Pentasaccharides :
• Contains 5 monosaccharide units.
Verbascose 3(Galactose)+Glucoce+Fructose

12. importance
 Oligosacchrides are not digest by human gastric glands.
 they are consumed by intestinal microflora.
 Importance
1. Help in growth of microflora that reduce the activity of
pathogens.
2. Reduce toxic metabolites
3. Prevent constipation(softens stools) and protect liver
functions
4. Reduce serum cholestrol level(increase glucose
metabolism)
5. Have anticancerous effects.( cause apoptosis)

13. Polysaccharides
They are polymers of monosaccharides units
with high molecular weights(up to million).
They are usually tasteless(non-sugars) and
form colloids with water
They serve as storage materials in plants and
animals
Starch in Plants
Glycogen in animals

14. Polysaccharides
They are of 2 types:
1. Homopolysaccharides (Homoglycans):
Contain monosaccharide units of a single type.
E.g. Starch, Glycogen, Cellulose.
2. Heteropolysaccharides (Heteroglycans):
Possess 2 or more different types of monosaccharides
units or their derivatives.
E.g. heparin, chondroitin sulfate.
 Heteropolysaccharides are of three types:
1. Mucopolysacchrides
2. Mucilages
3. hemicellulose

15. Isomerism
• The compounds possessing same molecular formula
but different structures are called isomers.
• Example.

16. Epimerism
• Epimers are two isomers of monosaccharides that
differ from each other in their configuration around
a single specific carbon(other than anomeric)
atom.