Transcript 2-d Enzymes and Activation Energy Notes

ENZYMES and
Activation Energy
OR: Why don’t you burn up
in flames when you eat!
What is Energy?
• Energy is the ability to cause
matter to move or change.
• All life processes are driven by
energy
• Where does all energy come from?
Chemical Reactions
• When bonds are broken and
reformed to make different
substances.
EX:
Reactants
Products
C6H12O6 + 6O2
6CO2 + 6H2O
What is Metabolism?
• Metabolism is the sum of all
chemical reactions in your body
- Metabolism is basically two
components
1.
2.
Breaking down foods for energy
Building new compounds to
make you
• Literally, you are
what you eat!
What is needed to
start a reaction?
reactant
Products
What is a Catalyst?
• A catalyst is anything that lowers
activation energy
There are basically two kinds:
1. Organic
2. Inorganic
• Organic catalysts are called Enzymes
Why is the activation
energy lower?
reactant
Products
Comparing Reactions
Which line would
represent a reaction
without an enzyme
present?
With an enzyme
present?
Reactant
Products
How Do Enzymes Work?
• Enzymes work
like a lock and
key.
• Specific
enzymes work
with specific
substrates.
enzyme
substrate
How Do Enzymes Work?
• Each substrate fits
into the enzyme’s
active site.
• Then the enzyme
controls chemical
reaction.
Induced Fit
• The reactant an enzyme acts on
is called the substrate
– Enzyme binds to substrate at
the active site to initiate rxn
Enzymes aren’t used up
• Enzymes are not changed by the
reaction
– used only temporarily
– re-used again for the same reaction
with other molecules
– very little enzyme needed to help in
many reactions
substrate
active site
product
enzyme
Enzymes can be affected by:
• Temperature:
Battery Acid
• pH:
0
Blood (7.5)
3
5
7
Neutral
• Concentration:
9
Bleach
11
13
Order of amino acids
• Wrong order = wrong shape = can’t do
its job!
chain of
amino acids
DNA
folded
protein
right shape!
folded
protein
chain of
amino acids
DNA
wrong shape!
Temperature
• Effect on rates of enzyme activity
–Optimum temperature
• greatest number of collisions between
enzyme & substrate
• human enzymes
– 35°- 40°C (body temp = 37°C)
–Raise temperature (boiling)
• denature protein = unfold = lose shape
–Lower temperature T°
• molecules move slower
• fewer collisions between enzyme &
substrate
Temperature
reaction rate
human
enzymes
37°
temperature
What’s
happening
here?!
How do cold-blooded
creatures do it?
pH
• Effect on rates of enzyme activity
–changes in pH changes protein
shape
–most human enzymes = pH 6-8
• depends on where in body
• pepsin (stomach) = pH 3
• trypsin (small intestines) = pH
8
pHintestines
stomach
pepsin
What’s
happening
here?!
reaction rate
trypsin
0
1
2
3
4
5
6
pH
7
8
9
10
11
12
13
14
Concentration
• Concentration is how much of
something there is in a particular
area.
• Rate is how fast a reaction occurs.
Increasing enzyme
concentration
ATP stores Energy
• ATP is the special carrier molecule that
stores energy available for cell use.
energy
P
ATP
ADP
energy
P
• ATP is the energy currency of the cell;
the energy source for all cell functions.