Worksheet for Topic 4 Biological molecules
4.1 Carbohydrates
Monosaccharide
Disaccharide
Polysaccharide
Sugar unit
One
Two
Many
Example
glucose
Maltose, sucrose
Starch, glycogen,
cellulose
Polysaccharide
Starch
Cellulose
Glycogen
Found in
Only in plants
Only in plants
Only in animals
Function
Energy storage in plants
Make up cell wall
Energy storage in animals
4.2 Lipids
•
Lipids are divided into fats (solids
•
Most fats (lipids) in the body are made up of triglycerides
Triglyceride = 1
glycerol
at room temperature) and oils (liquids
+ 3 fatty
at room temperature)
acid
4.3 Proteins

The basic unit of protein is called amino acid

There are about 2
.
0 different amino acids.
The structure of amino acid
They all contain the same basic structure but the ‘R’ group is different for each one
The different sequences of amino acids cause the polypeptide chains to fold in different ways and this

gives rise to the different shapes of proteins.
Example of protein:

enzyme, antibody
4.4 Food test
Molecules
Starch
Reducing sugar
Protein
Fats
Vitamin C
Reagent
Iodine solution
Benedict’s solution
Biuret solution
Ethanol & water
DCPIP
Color change
Brown→black blue
Blue→brick red
Blue→
Clean→cloudy
Colorless→blue
purple/violet
(emulsification)
Notice
Heating required
4.5 DNA structure

Nucleus, chromosome, DNA, gene
(A): Adenine
(C): Cytosine
(T): Thymine
(G): Guanine
Base pairing rules:
4.6 Water

Water is important as a solvent

Dissolved substances can be easily transported around organisms (digested food molecules, urea, salts)

Water is also an important part of the cytoplasm and plays a role in ensuring metabolic reactions
can happen as necessary in cells