National 4 and 5 proteins enzymes and their use in industry
Nat 5- Protein structure and function
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Proteins all have a 3-dimensional shape which is important in determining the
proteins function
this shape is determined by the order of amino acids
the order of amino acids is determined by the order of the bases on the
DNA
Therefore, the structure and function of a protein is dictated by the order
of bases on the DNA strand.
The variety of protein shapes and functions arise from the sequence of amino
acids. There gives rise to 3 different types of protein shape
Proteins have many functions
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enzymes
hormones e.g. insulin to regulate blood glucose levels
antibodies (produced by white blood cells to fight infection)
structural e.g. found in cell membrane and collagen in bone, tendon and
ligament
transport protein e.g. haemoglobin (found in red blood cells for
transporting oxygen)
National 4 and 5- Investigating Enzymes
A catalyst is a substance that speeds up chemical reactions but is not
changed in the process of doing so.
Enzymes are made of protein and can be thought of as biological catalysts as
they are found in living cells and speed up chemical reactions within the cell.
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Enzymes are essential to living cells because without enzymes the cells
chemical reactions would not proceed quickly enough to allow the cell to live.
Examples of enzyme breakdown reactions
Substrate
Enzyme
Catalase
Hydrogen Peroxide
End product(s)
Water + Oxygen
Amylase
Starch
Maltose
Pepsin
Protein
Fats
Peptides
Lipase
Fatty acids + Glycerol
Examples of enzyme synthesis (building up) reactions
Substrate
Glucose
Enzyme
Phosphorylase
End product(s)
Starch
Specificity of enzymes
Every enzyme will act upon one substrate only and is said to be specific
to that substrate, e.g. amylase will act on starch and nothing else,
therefore amylase is specific to starch.
National 5 - Effects of temperature and pH on enzymes
Temperature
 Every enzyme has a temperature at which it is most active (works best).
 As the temperature is decreased below this value the enzyme becomes
less and less effective until it is almost inactive.
 As the temperature is increased above this value the enzyme becomes less
and less effective until it is denatured (destroyed).
e.g. Pepsin breaks down most protein at 37oC, breaks down almost no protein
at 4oC or below and is denatured at 60oC or above.
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pH
 Every enzyme has a pH at which it is most active (works best).
 As the pH is decreased below this value the enzyme becomes less and less
effective until it is almost inactive.
 As the pH is increased above this value the enzyme becomes less and less
effective until it is almost inactive.
 pH’s which are very different from an enzymes optimum will denature the
enzyme.
e.g. Catalase will work from pH 7 to 11 but works best at pH 9. Most
enzymes work best at pH 7 with pepsin being an exception as it works
best at pH 2-3.
Optimum conditions
The temperature at which an enzyme is most active is said to be that
enzymes optimum temperature.
The pH at which an enzyme is most active is said to be that enzymes optimum
pH.
Each enzyme has a particular optimum temperature and pH at which it is most
active. This temperature and pH is different for each enzyme depending
upon the living cell it is in.
National 4-Biological detergents
Biological detergents contain enzymes produced by bacteria.
Biological detergents remove stains because the enzymes they contain act upon
the substance that is causing the stain (e.g. blood, grass) and break it down by
digesting it.
As the enzymes would be denatured at high temperatures, biological detergents
work best at lower temperatures (around 40oC).
Advantages of biological detergents
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1. They will break down and remove biological stains like grass and blood that
non-biological detergents cannot.
2. They save money on the cost of fuel and prevent fabrics being damaged
because they work best at low temperatures.
Biological detergents remove stains because the enzymes they contain act upon
the substance that is causing the stain (e.g. blood, grass) and break it down by
digesting it.
As the enzymes would be denatured at high temperatures, biological detergents
work best at lower temperatures (around 40oC).
National 4- Production of cheese
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Cheese and yoghurt production requires lactic acid to make the milk curdle
Certain bacteria are added to the milk and they produce the required lactic
acid by fermentation
Rennet is an enzyme that clots the milk and is used in cheese making.
Check point B2
Level 4 E&O
I have taken part in practical activities which involved the use of enzymes and
microorganisms to develop my understanding of and their use in industry
Nat 4
Properties of enzymes and their use in industry
Enzymes are found in living cells. They are specific, speed up reaction and remain
unchanged by the reaction. Enzymes build up and break down molecules. Enzymes xan be
used in a range of biological industries.
Enzymes are used in the detergent industry and in cheese making (rennet)
Nat 5
5 Proteins and enzymes
a. The variety of protein shapes and functions arises from the sequence of amino acids.
b. Functions of proteins to include structural, enzymes, hormones, antibodies and
receptors.
c. Enzymes function as biological catalysts and are made by all living cells. They speed up
cellular reactions and are unchanged in the process. The shape of the active site of
enzyme molecules is complementary to a specific substrate.
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d. Each enzyme works best in its optimum conditions. Enzymes and other proteins can be
affected by temperature and pH. Enzymes can be denatured, resulting in a change in
their shape, which will affect the rate of reaction.
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