GCSE Enzymes
GCSE Enzymes
GCSE Enzymes
Proteins account for more than 50% of the dry weight of cells
and are VITAL in almost everything organisms do!
PROTEINS!
Organic
molecules
Containing
C, H, O and N
Structural support
Storage
Signaling
Defense
Transport
Movement
Proteins have
many vital
functions,
including
ENZYMES
HORMONES
Collagen
(i.e. enzymes hydrolyze large food molecules: digestive enzymes) others help make (synthesize) large
molecules.
B2_1.26_Enzymes as biological
catalysts
B2_1.27_Enzymes catalyse
chemical reactions
B2_1.29_Enzymes are highly
specific for their substrate
B2_1.30_Lock-and-key
hypothesis
The
reactant
is
called the substrate.
The enzyme has a
specific indentation
called an active site,
which helps it to
recognise
that
substrate.
Enzyme specificity
Use the diagram
(left) to help you
to explain why
each enzyme will
only catalyse one
particular
reaction.
Substrate B
B2_1.28_Factors affecting
enzyme action
B2_1.31_Enzymes can be
denatured
Temperature
pH
Concentration
Temperature &
pH
Most enzymes function best
at normal Body temperature:
37C
High
temperatures
will
usually result in an enzymes
denaturation
Most enzymes like near
neutral pH (6 to 8)
Denaturation is defined as a
perminant change in the
tertiary
(3-dimensional)
structure of a protein
When
an
enzyme
is
denatured it is no longer able
to function
2. The Effect of pH
How pH affects
enzyme activity
An enzymes catalytic activity
is affected by how acidic or
alkaline its environment is.
The majority of enzymes
work
best
in
neutral
conditions. However, some
prefer acidic and others
prefer alkaline conditions.
2. How pH affects
enzyme activity
Similar to temperature, the
active site of an enzyme can be
changed by conditions that are
either too acidic or too alkaline.
If the active site of the enzyme is changed (i.e. it is denatured) then the
substrate can no longer bond/attach to the active site of the enzyme.
Therefore no reaction can take place and no product produced
3. Enzyme
Concentration
Substrate Concentration
The more
substrate in the
solution the
greater the
chance of a
substrate
molecule finding
an active site, and
the faster the
rate of reaction
up to a maximum
when all active
sites are fully
used.
Free
Energy
Without Enzyme
With Enzyme
Products
Which
they are
most effective at
means
Less energy
is used
lower
temperatures,
e.g around 30OC.
(heating
water / production
This has
other
benefits:
of many
carbon
emissions)
Dyes in fabrics are less
Less energy is used
likely to run out of
(heating water / production
fabrics
of carbon emissions)
Clothes are less likely to
Dyes in fabrics are less
shrink in the wash.
likely to run out of
fabrics
Clothes are less likely to
shrink in the wash.