1. Proteins, catalysts and
enzymes
WALT: To understand the role of
enzymes.
WILF:
Describe what a protein is and list uses
in the body. (C)
Describe the role of enzymes as
biological catalysts. (B)
Explain how enzymes work in reference
to the lock and key hypothesis. (A/A*)
Sunday, 28
September 2014
Keywords
Catalysts
Enzymes
Active site
Substrate

2. Proteins
Proteins are very important in your body.
They are made up of long chains of amino
acids.
Amino acids
(monomer)
Protein
(polymer)

3. Proteins
Proteins carry out a range of functions in
the body:
~ structural e.g. Muscle tissue
~ hormones e.g. Oestrogen
~ antibodies
~ enzymes

4. B1
Link!
Hormones and the menstrual
cycle (2.3)
Keywords
Ovulation
Period
FSH
Oestrogen
Progesterone
C: Name the structures in the
body that release hormones.
B: Describe what the
menstrual cycle is and its
average length.
A/A*: Explain the roles of FSH
and oestrogen in the menstrual
cycle.

5. Controlling the rate of
reactions
The rate of a
chemical reaction
can be increased
by using chemicals
called catalysts.
A catalyst speeds up the
rate of reaction but it is not
used up in the reaction.
e.g. Iron is the catalyst used in
the production of ammonia.

6. Enzymes
Enzymes are biological
catalysts.
They increase the rate of
chemical reactions in the body.
They are specific.
The long amino
acid chain is
folded forming
a specific 3d
shape

7. Enzymes
1) Build small molecules into large molecules:
e.g. Amino acids  Proteins OR Glucose  Starch
2) Break large molecules down into smaller ones:
e.g Starch  Glucose OR Proteins  Amino acids
3) Change one molecule into another
e.g. Sugars: Glucose  Fructose
All of these reactions are speeded up by
enzymes!

8. The ‘lock and key’ hypothesis
Substrate
molecules
Active site Enzyme
Reaction happens (bonds
either made or broken)
Product
Enzymes have a specific 3D
structure
Enzyme-substrate
complex

9. The ‘lock and key’ hypothesis
Tasks: 1. Glue in and label your diagram
which illustrates how enzymes work.
2. Using the keywords below explain:
a) how enzymes work
b) why they are specific.
Keywords
enzyme substrate active site
3D shape specific reaction
product
enzyme-substrate complex

10. Hydrogen Peroxide
Hydrogen peroxide is a toxic chemical produced as a by-product
to the metabolic reactions (chemical reactions)
in our cells.
It has to be broken down into the harmless products.
The enzyme catalase speeds up this reaction.
Catalase
2H2O2 --------------> 2H2O + O2

11. Hydrogen Peroxide
1.Catalase is an enzyme found in liver
tissue. Define the term enzyme.
2.Catalase breaks down hydrogen
peroxide into oxygen and hydrogen.
What are the substrates and
products in this reaction?
3. Explain the importance of this
reaction in the body.
4.Manganese (IV) oxide is an industrial
catalyst. Look at the graph on pg 165
and describe its effect on the
breakdown of hydrogen peroxide.

12. Enzymes Summed Up!
A catalyst will speed up a
reaction...
Living organisms produce
biological catalysts called...
All enzymes are made up of...
The substrate of an enzyme binds
to the...
Each type of enzyme has a
specific...
...active site.
...proteins.
...3d shape.
...but is not used
up itself.
...enzymes.