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How Enzymes Work
How Enzymes Work
Cells within a
person are in need
of glucose in order
to function properly
How Enzymes Work
Table sugar
(sucrose) is
ingested by a
person.
How Enzymes Work
Within a person’s
small intestine,
the enzyme
sucrase is
available with
open active sites.
These sites will
break sucrose
down into glucose
and fructose.
Active site
Sucrase
How Enzymes Work
The ingested
sucrose eventually
makes its way into
the small intestine.
Sucrose
(substrate)
Sucrose is the
substrate of the
enzyme sucrase.
Sucrase
(enzyme)
How Enzymes Work
When the two
collide just right,
the sucrose
molecule will fill in
the enzyme’s
active site.
Sucrose
Sucrase
How Enzymes Work
Part of the
enzyme then
changes its
shape. This
weakens the bond
between the two
sugars that make
up sucrose.
Sucrose
Sucrase
How Enzymes Work
Part of the
enzyme then
changes its
shape. This
weakens the bond
between the two
sugars that make
up sucrose.
Sucrase
How Enzymes Work
This is just one
model showing
how scientists
view the
sucrose &
sucrase
complex.
Sucrase
How Enzymes Work
The weakened
glycosidic bond is
positioned such
that it can readily
react with a water
molecule.
Sucrase
How Enzymes Work
The weakened
glycosidic bond is
positioned such
that it can readily
react with a water
molecule.
Sucrase
How Enzymes Work
Eventually, a
water molecule
will collide with
the weakened
glycosidic bond.
How Enzymes Work
The hydrolytic
reaction between
the weakened
glycosidic bond
and water
changes the
enzyme’s shape.
How Enzymes Work
The hydrolytic
reaction between
the weakened
glycosidic bond
and water
changes the
enzyme’s shape.
How Enzymes Work
Glucose
The substrate
sucrose has
now been split
into two
different
products:
glucose and
fructose.
Fructose
How Enzymes Work
The enzyme
sucrase returns
to its original
shape and is
ready for the
next sucrose
molecule.
Glucose
Fructose
How Enzymes Work
Glucose and
fructose are
used by the cell
as sources of
energy.
Glucose
Fructose
How Enzymes Work
The amount of
energy needed
for water to
break sucrose
into glucose and
fructose is called
activation
energy.
Energy
Sucrose
Glucose & Fructose
Sucrose
Reactants
Products
Reaction pathway
How Enzymes Work
Sucrose
Activation energy
H2 O
Energy
The amount of
energy needed
for water to
break sucrose
into glucose and
fructose is called
activation
energy.
Glucose & Fructose
Glucose
Reactants
Fructose
Products
Reaction pathway
How Enzymes Work
Medium
Energy
Quantity
At average cell
temperatures,
only a few water
molecules have
enough energy
to break the
glycosidic bond
of sucrose.
Low
Energy
High
Energy
Energy
How Enzymes Work
Sucrose
Glucose & Fructose
Activation energy
Energy
With the
enzyme sucrase
weakening
sucrose’s
glycosidic bond,
the energy of
activation is
effectively
lowered
Sucrose
Glucose
Reactants
Effects of Sucrase
Fructose
Products
Reaction pathway
How Enzymes Work
Medium
Energy
Quantity
This lower
activation
energy means
that more
molecules of
water will have
enough energy
to break the
bond.
Low
Energy
High
Energy
Energy
How Enzymes Work
The result is that the presence of sucrase causes an
increase in the amount of glucose and fructose produced.
Product production
Without
Sucrase
With
Sucrase