Higher Human Biology
Unit 1 – Cell Function and Inheritance
Proteins
The Role of Enzymes
Success criteria

1.
2.
3.
By the end of this lesson we will be able
to:
State what elements are found in
proteins
Describe what is meant by primary,
secondary and tertiary structure of
proteins.
Give examples of different types of
proteins and their uses.
Protein structure

Aim: The aim of this lesson is to
understand the structure of proteins,
their component parts and
their functions.
Success criteria

1.
2.
3.
By the end of this lesson we will be able
to:
State what elements are found in
proteins
Describe what is meant by primary,
secondary and tertiary structure of
proteins.
Give examples of different types of
proteins and their uses.
Protein elements

Proteins are large organic molecules
made up of the elements Carbon,
Hydrogen, Oxygen and Nitrogen.

Proteins will also often contain sulphur.
The whole picture

Ball and stick model
Grey = Carbon
Red = Oxygen
Blue = Nitrogen
Yellow = Sulphur
Hydrogen not shown
Primary structure

The sub-units of proteins are known as
amino acids which are linked together
into long chains by peptide bonds
Peptide bond
Valine
Leucine
Isovaline
Alanine
Primary structure

There are 20 exciting amino acids to
choose from when building a protein.
Build a protein

Use the amino acid blocks to build a chain
which is 20 amino acids long.

You can use an amino acid more than
once.
Primary structure

The amino acids in the chain and the
order in which they appear is the
primary structure of a protein.
Valine

Leucine
Isovaline
Alanine
In living things, this primary structure
does not happen by chance but is coded
for by DNA.
Secondary structure

When the chain is complete it will be
long.
Secondary structure

Weak hydrogen bonds will form between
some amino acids in the chain making it
coil into a helix.
Hydrogen bond
Secondary structure

The way a protein coils up into a helix is
the secondary structure.
When a protein winds
up into a coil. This is
called an ∂ Helix.
Proteins with secondary
structure are fibrous e.g.
Collagen found in
cartilage,tendon, skin,
and bone.
Secondary structure
Helices can also be
twisted around each other
layers with ‘thicken’ the
connective fibres e.g.
• Collagen – 3 alpha
helices twisted together
• Keratin which makes up
hair -7 alpha helices
twisted together
The diagram above shows the three
collagen helices twisted together
Tertiary structure
Proteins can also
wind up into
tangled shapes
using a variety of
additional bonds.
This will form a
globular protein.
Keratin in hair has disulphide bonds. If Enzymes, hormones and antibodies all
you light a single hair you will smell the have a globular structure
sulphur
Tertiary structure
A globular protein
can sometimes
contain non
protein parts in
the tertiary
structure. This
forms a
Non protein parts
conjugated
Haemoglobin is an important oxygen
protein.
carrying pigment with a conjugated structure
containing iron
Examples of proteins
Protein name
Type of protein
Role
Collagen
Fibrous
Found in skin
Actin
Fibrous
Muscle cell filaments
Myosin
Fibrous
Muscle cell filaments
Amalase (Enzyme)
Globular
Breakdown of starch
into maltose
Testosterone
(Hormone)
Globular
Produces male gender
characteristics
Haemoglobin
Conjugated globular
Found in red blood cells.
Carries oxygen.
Now try the following
Name the elements are found in all proteins
2. Describe what is meant by each of the primary
structure of proteins.
3. Name the bond between amino acids.
4. What additional bond gives secondary
structures their shape?
5. What is the main shape formed using secondary
structure?
6. Give two examples of proteins made up
exclusively from proteins with secondary
structure
1.
7. Proteins can also take up a more complex tertiary structure. Describe
this.
8. Give two examples of proteins with a tertiary structure and state what
each protein is used for.
9. Haemoglobin is an example of a protein with a conjugated structure.
Explain what is meant by this.
10. Give the level of structure and the function of each of the following
proteins:



Actin
Testosterone
Keratin
Haemoglobin