Download on the enzyme

ENZYMES
III. Why are enzymes necessary
for life?
A.
Enzymes help maintain homeostasis
Metabolism (chemical reactions) requires certain conditions to
occur. Enzymes regulate metabolism, allowing life to continue.
Enzymes speed up reactions, making an enzyme a
biological catalyst.
III. Why are enzymes necessary
for life?
A.
Enzymes help maintain homeostasis
Metabolism (each reaction) has a small range of
temperature and pH at which it can proceed. Each
reaction also needs some energy to begin. This is called
activation energy. Enzymes allow reactions to occur
at lower activation energy (body temperature).
Chemical Reactions MYP

Chemical Reactions
 Reactions
that release energy will occur
spontaneously


(2)H2 (gas burning) + O2  (2)H2O(water vapor)
Reactions that absorb energy will not occur
WITHOUT a source of energy

(2)H20 (water vapor)  O2 + (2)H2
Will release a lot of energy as HEAT, light, or sound
 Example: explosions

Fill It In …
The main job of enzymes:
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Explanation of graph:
B. The structure of an enzyme determines its function
Enzymes are usually proteins. Proteins have a definite 3-D
structure based on how the amino acid chains fold
Enzyme Animation
B. The structure of an enzyme determines its function
On the enzyme, there is a
place where the target
molecule can attach. This
place is called the active
site. The target
molecule/chemical is the
substrate.
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Simple picture of an enzyme and substrate
(label active site):
B. The structure of an enzyme determines its function
If the enzyme’s active site changes shape too much, the
substrate will not fit. An enzyme may change shape if it
is denatured by a change in temperature, pH, or
salinity. This means the enzyme will not be able to
speed up the reaction.
Effects of denaturation



What is the optimal temperature for this enzyme?
What does “optimal temperature” mean?
Why does the enzyme stop working around 630C?
Effects of denaturation



Different enzymes work best at different pH
Which enzyme works best at a neutral pH?
Which enzyme works best in an acidic environment?
Enzymes mediate (help) chemical reactions using a
specific chemical pathway (series of steps).
a.
b.
c.
The enzyme collides with the substrate.
The enzyme and substrate fit together at the
active site like a lock and key.
The enzyme changes the substrate in some way
i.
d.
It may help break the substrate apart by
stressing bonds.
ii. It may hold two (or more) substrates
together closely so the two parts interact.
The enzyme and the substrate (now product)
separate.
Enzyme Lock and Key
Enzyme-Mediated Pathway
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Enzymes and substrates are like a …
C. Enzymes have distinguishing characteristics
Enzymes are specific. This
means enzymes will catalyze
only one specific reaction
because only certain
substrates fit due to the
shape of the active site.
http://www.youtube.com/wat
ch?v=V4OPO6JQLOE
Substrate
Enzyme
Sucrose
Sucrase
Lactose
Lactase
Amylose
Amylase
Lipid
Lipase
Protein
Protease
How are the names of the enzymes similar?
C. Enzymes have distinguishing characteristics
Enzymes are reusable.
Notice in the diagram
above that the enzyme did
not change shape or split.
This means it can now fit
with another substrate or
set of substrates and
repeat its role in
speeding up the
reaction.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature?
.
What organic compound are most enzymes?
.
What is the name of the target chemical on
which the enzyme works?
Is the active site located on the enzyme or the
substrate?
Name two characteristics of enzymes.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature? ACTIVATION
ENERGY
What organic compound are most enzymes?
.
What is the name of the target chemical on
which the enzyme works?
Is the active site located on the enzyme or the
substrate?
Name two characteristics of enzymes.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature? ACTIVATION
ENERGY
What organic compound are most enzymes?
PROTEIN
What is the name of the target chemical on
which the enzyme works?
Is the active site located on the enzyme or the
substrate?
Name two characteristics of enzymes.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature? ACTIVATION
ENERGY
What organic compound are most enzymes?
PROTEIN
What is the name of the target chemical on
which the enzyme works? SUBSTRATE
Is the active site located on the enzyme or the
substrate?
Name two characteristics of enzymes.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature? ACTIVATION
ENERGY
What organic compound are most enzymes?
PROTEIN
What is the name of the target chemical on
which the enzyme works? SUBSTRATE
Is the active site located on the enzyme or the
substrate? ON THE ENZYME
Name two characteristics of enzymes.
Check Yourself!
1.
2.
3.
4.
5.
What do enzymes lower, allowing reactions to
occur at body temperature? ACTIVATION
ENERGY
What organic compound are most enzymes?
PROTEIN
What is the name of the target chemical on
which the enzyme works? SUBSTRATE
Is the active site located on the enzyme or the
substrate? ON THE ENZYME
Name two characteristics of enzymes.
SPECIFIC AND REUSABLE