enzymes and activation energy or: why don’t you burn up in flames when you eat!
TRANSCRIPT
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
• Literally, you are what you eat!
1. Breaking down foods for energy
2. Building new compounds to make you
What is needed to start a reaction?
En
ergy
ab
sorb
ed
Act
ivat
ion
en
ergy
reactant
Products
En
ergy
rel
ease
d
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?
En
ergy
ab
sorb
edE
ner
gy r
elea
sed reactant
Products
Activation energy
En
erg
y a
bs
orb
edE
ner
gy
re
lea
sed
Reactant
Products
Comparing Reactions Which line would represent a reaction without an enzyme present?
With an enzyme present?
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
enzyme
substrate product
active site
Enzymes can be affected by:
• Temperature:
• pH:
• Concentration:
0 3 75 9 11 13
Neutral
Battery Acid BleachBlood (7.5)
Order of amino acids• Wrong order = wrong shape = can’t do its job!
DNA
DNA
chain ofamino acids
chain ofamino acids
foldedprotein
foldedprotein
right shape!
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
37°
Temperature
temperature
reac
tion
rat
eWhat’s
happening here?!
humanenzymes
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
7
pH
pH
reac
tion
rat
e
20 1 3 4 5 6 8 9 10
stomachpepsin
intestinestrypsin
What’s happening here?!
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.
• ATP is the energy currency of the cell; the energy source for all cell functions.
ATP
ADPP P
energy energy