II- Organic molecules
• Organic molecules are those that:
1) formed by the actions of living things.
2) have a carbon backbone.
• Each organic molecule group has small molecules (monomers)
that are linked to form a larger organic molecule
(macromolecule).
• Monomers can be joined together to form polymers that are
the large macromolecules made of three to millions of
monomer subunits.
(Carbohydrates, Lipids, Proteins and nucleic acids)
Mono-mer
Di-mer
Poly-mer
Polymer is a long molecule consists of a chain of similar building
molecules (monomers) covalently bounded together.
Polymer can be built up by linking its monomers by dehydration
(removing H2O).
Polymer can be broken down to its monomers by hydrolysis
(adding H2O).
1- Carbohydrates
Fuel and Building Material
1.Sugars, the smallest carbohydrates, are fuel
and carbon sources.
2.Polysaccharides, the polymers of sugars,
have storage and structural functions
1- Carbohydrates
Fuel and Building Material
• Monosaccharides, are the simplest
carbohydrates (simple sugars).
• Disaccharides, double sugars, consist of two
monosaccharides joined by dehydration.
• Polysaccharides, are polymers of many
monosaccharides.
1- Monosaccharides
Hexose Sugar
Pentose Sugar
Triose Sugar
H
O
H
O
C
H
H
H
C
OH
H
C
OH
H
Glyceraldehyde
H
H
C
OH
C
OH
C
C
OH
OH
H
Ribose
OH
C
C
H
H
C
O
OH
C
H
H
C
OH
H
C
OH
H
C
OH
H
Fructose
2- Disaccharides
1- Maltose
2(C6H12O6)
2 Glucose
C12H22O11
Maltose
+ H2O
2- Lactose (milk sugar): consists of Glucose + Galactose.
3- Sucrose (table sugar): consists of Glucose + Fructose.
3- Polysaccharides
• Consisted of few hundreds to few thousands
of monosaccharides.
They are two types:
1- Storage: Provide sugar for cell by hydrolysis.
2- Structural : Serve as building materials for the organism.
A)- Storage Polysaccharides
I- Starch (in plants)
A storage polysaccharide of plants (within plastids).•
It is consisted of thousands of  glucose molecules.•
Potatoes and grains are the major source of starch. •
II- Glycogen (in animals)
Stored in animal cells (e.g. liver and muscle cells in Human).•
It is consisted of thousands of glucose molecules.•
B)- Structural Polysaccharides
I- Cellulose
• It is the building material of plants (cell wall).
• It is consisted of thousands of β glucose molecules.
• Human cannot digest it, but some bacteria and protozoa can
(e.g. in Termites and Cows stomach).
II- Chitin
• It is the building material of the cuticle in insects.
• It is consisted of thousands of glucose molecules with a N atom
in one end.
• It is used to manufacture the surgical threads.
The Summary
Carbohydrates
No. of C atoms
Triose (3C)
Glyceraldehyde
Pentose (5C)
Ribose
Monosaccharides
Glucose & Fructose
No. of sugar molecules
Hexose (6C)
Glucose
Disaccharides
Maltose & Sucrose
Storage
Starch (in plants)
&
Glycogen (in animals)
Polysaccharides
Structural
Cellulose (in plants)
&
Chitin (in insects)