Chapter 3-enzymes
Enzyme "biological catalyst that speeds up the rate of a chemical reaction but remains
unchanged at the end of the reaction .
Globular proteins
·
Many enzymes end with -ase
Intracellular work inside cells
enzymes .
Extracellular enzymes are secreted by cells and
catalyse reactions outside cells .
↳
for example digestive enzymes
,
in the
gut .
Some organisms secrete
enzymes outside their bodies
↳ for
example , fungi in order to
digest food on which they are growing .
Mode of action of
enzymes
enzymes are coiled into a precise three-dimensional Shape .
Hydrophilic R- the outside of the molecule make them soluble water in the
groups on in
Cytoplasm .
Active
·
Site area molecule where the substrate bind
on an
enzyme can
-
.
Lock and
key hypothesis
The Shape
-
of the active site allows the substrate to fit
perfectly .
Idea that the
enzyme has an exact fit Shape .
Substrate =
Key
Lock enzyme
·
=
The
-
Substrate is held in place by temporary bonds which form between the Substrate and Some of the R-groups
of the the
enzymes amino acids 3 enzyme-substrateComplex .
Each
-
enzyme will act on
only one
type of substrate molecule, due to the Shape of the active site .
Induced fit hypothesis
:
-
hypothesis for
enzyme action ; the Substrate is a
complementary shape to the active Site of the
enzyme ,
but not an exact fit
-
the enzyme , or substrate changes shape Slightly ,
to ensure a perfect fit .
catalyst
-
makes more efficient .
, Lysozyme
-found in tears
,
Saliva and other secretions .
Acts
-
as natural defence
against bacteria
, by breaking the polysaccharide Chains that form the cell walls of bacteria
-Hydrolysis reaction
Enzymes reduce activation energy
Enzymes
-
increase the rate at which Chemical reactions occur .
Activation energy
·
energy that must
-
be provided to make a reaction take place.
-AEL =
faster reaction
↳
enzymes decrease the AE
by holding the substrates in a
way their molecules can react more
easily .
Investigating the progress of an
enzyme catalysed reaction
1st
way Measuring the rate of formation of a product
for example :
the enzyme Catalase
This enzyme
·
is found the tissues of most
in
living things and catalyses the breakdown of
hydrogen
peroxide into water and
oxygen .
It's
·
toxic so it must be rid off
got quickly
Oxygen released can be collected and measured
Rate at which a reaction occurs depends on
:
how
·
many enzyme molecules there are
·
Speed at which the
enzyme can convert the substrate into product, release it then bind
again
As substrate is converted into product there fewer substrate molecules to bind with so reaction
gets
more ,
are
enzymes ,
Slower and eventually stops .
Enzyme "biological catalyst that speeds up the rate of a chemical reaction but remains
unchanged at the end of the reaction .
Globular proteins
·
Many enzymes end with -ase
Intracellular work inside cells
enzymes .
Extracellular enzymes are secreted by cells and
catalyse reactions outside cells .
↳
for example digestive enzymes
,
in the
gut .
Some organisms secrete
enzymes outside their bodies
↳ for
example , fungi in order to
digest food on which they are growing .
Mode of action of
enzymes
enzymes are coiled into a precise three-dimensional Shape .
Hydrophilic R- the outside of the molecule make them soluble water in the
groups on in
Cytoplasm .
Active
·
Site area molecule where the substrate bind
on an
enzyme can
-
.
Lock and
key hypothesis
The Shape
-
of the active site allows the substrate to fit
perfectly .
Idea that the
enzyme has an exact fit Shape .
Substrate =
Key
Lock enzyme
·
=
The
-
Substrate is held in place by temporary bonds which form between the Substrate and Some of the R-groups
of the the
enzymes amino acids 3 enzyme-substrateComplex .
Each
-
enzyme will act on
only one
type of substrate molecule, due to the Shape of the active site .
Induced fit hypothesis
:
-
hypothesis for
enzyme action ; the Substrate is a
complementary shape to the active Site of the
enzyme ,
but not an exact fit
-
the enzyme , or substrate changes shape Slightly ,
to ensure a perfect fit .
catalyst
-
makes more efficient .
, Lysozyme
-found in tears
,
Saliva and other secretions .
Acts
-
as natural defence
against bacteria
, by breaking the polysaccharide Chains that form the cell walls of bacteria
-Hydrolysis reaction
Enzymes reduce activation energy
Enzymes
-
increase the rate at which Chemical reactions occur .
Activation energy
·
energy that must
-
be provided to make a reaction take place.
-AEL =
faster reaction
↳
enzymes decrease the AE
by holding the substrates in a
way their molecules can react more
easily .
Investigating the progress of an
enzyme catalysed reaction
1st
way Measuring the rate of formation of a product
for example :
the enzyme Catalase
This enzyme
·
is found the tissues of most
in
living things and catalyses the breakdown of
hydrogen
peroxide into water and
oxygen .
It's
·
toxic so it must be rid off
got quickly
Oxygen released can be collected and measured
Rate at which a reaction occurs depends on
:
how
·
many enzyme molecules there are
·
Speed at which the
enzyme can convert the substrate into product, release it then bind
again
As substrate is converted into product there fewer substrate molecules to bind with so reaction
gets
more ,
are
enzymes ,
Slower and eventually stops .
