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A level Biology AQA Biological molecules notes
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- Enzyme action regenerates-STRUCTURE OF ENZYMES
All enzymes
-
are globular proteins .
Most
enzymes are very large molecules but only a small part of them is
-
involved in catalysis This is called the active site
. and it may consist of just a
few amino acids
-
The remainder of the amino acids maintain the precise shape of the enzyme and the
active site .
ROLE OF EN2Y 1ES
( building up ) and catabolic (
Enzymes catalyse breaking down)
a
both anabolic
reactions .
enzyme bonds the substrate molecule (s )
•
The active site of an of a biochemical
reaction ,
and is critical to its
specificity and catalytic activity
reaction For example , catalase
'
Many enzymes are specific to just one .
only
catalyses the breakdown of hydrogen peroxide .
A toxic
by-product of metabolism .
intracellularly
-
Enzyme action occurs both and extracellular ly .
intracellular process that involves many enzymes
'
DNA replication is an
,
such as
DNA polymerase and DNA
ligase .
•
Some intracellular reactions occur on a membrane .
The
synthesis of ATP
by
ATPase during respiration ,
for example ,
occurs across the inner
membrane of mitochondria .
Enzymes catalyse the reactions the activation energy
-
by lowering
Activation energy to break the bonds of the
-
the input energy required
( Ea ) reactants and start the reaction .
INDUCED FIT MODEL
theory
9
unlike the lock and key theory the induced fit proposes that the
active site is not
initially an exact fit for the substrate molecule
As the substrate moves into the active site forces between the two
•
molecules distort the
enzyme and its active site so it tightly envelops
the substrate .
Forming an enzyme substrate complex -
.
substrate complex lowers the activation
•
The formation of an
enzyme
-
energy of the reaction .
•
once the reaction is complete ,
the products leave the active site and
the back to its original shape
enzyme changes .
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