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Ch. 6.3 Enzymes
Review Energy & Reactions
Reactant Products
Reactants Product
Exergonic reaction
Endergonic reaction
Have less useable energy
Has more useable energy Have less useable energy
Has more useable energy
This reaction releases energy
Energy absorbedBoth reactions require energy to start = Activation Energy
spontaneous
spontaneous
Can be
Cannot be
Graphs of Energy Change
Activation energy
Wor
k is
put
inF
un is
rel
ease
d
More work than fun
More fun than work
Mon
ey is
spe
ntM
oney
is r
ecei
ved
Spent more than received
Received more than spent
Initial Investment
Initial Investment
Good InvestmentBad InvestmentTime for reaction
En
erg
y
Catalysis The process of
speeding up a reaction – how? Lowers the
activation energy Works on both
exergonic and endergonic
“Catalyze” “Catalyst” Most important
biological catalyst =
By Enzymes
Enzymes (a type of protein) Quick Review
Protein is a polypeptide chain of amino acids folded into a shape
Shape provides function
Enzymes subject to denaturation
(unfolding)
A.A. A.A. A.A. A.A. A.A.
If denatures (unfolds), then loses shape and loses function (loses site to bind)
Polar A.A. NonPolar A.A. Polar A.A.
Animations http://highered.mcgraw-hill.com/classware/ala.do?isbn=0072986670&a
laid=ala_1048056&showSelfStudyTree=true http://highered.mcgraw-hill.com/classware/ala.do?isbn=0072986670&a
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How Enzymes Work Enzyme binds to substrate (“special” name
for reactants that are catalyzed) Fit together like “lock and key”(shape determines…)
May cause an “induced fit” – enzyme changes shape to better “hug” substrate Enzyme will push/pull on substrate(s) to weaken
bond (more likely to break) or make bond more likely to form Lowers activation energy by making it more
physically likely for reaction to occur… Active Site: area on enzyme (space or
groove) where substrate binds to
The reactants an enzyme binds with are called
A. proteins
B. Substrates
C. Active sites
D. catalysts
prote
ins
Substrate
s
Active
sites
catalysts
0% 0%
13%
88%
The place where a substrate and an enzyme meet is called
the
A. Enzyme-substrate complex
B. Catalyst site
C. Active site
D. P-site
Enzyme-su
bstrate
complex
Catalys
t site
Active
site
P-site
0% 0%
100%
0%
When enzyme changes its shape to better fit its
substrate this is calledA. Active fit
B. A catalyzed reaction
C. Induced fit
D. An allosteric reaction
Active
fit
A catalyze
d reacti
on
Induced fit
An alloste
ric re
action
0% 0%
100%
0%
The energy needed to start a chemical reaction is called
A. Endothermic energy
B. Exothermic energy
C. Activation Energy
D. Allosteric Energy
Endotherm
ic energ
y
Exoth
ermic
energy
Activa
tion Energy
Alloste
ric Energy
0% 0%
100%
0%
Which shape is the enzyme?
A B C D
87%
0%0%
13%
1. A
2. B
3. C
4. D
A A A
BC
D D
Which shape is the active site?
A B C D
6% 6%
88%
0%
1. A
2. B
3. C
4. D
A A A
BC
D D
Which shape is the product?
A B C D
0% 0%0%
100%
1. A
2. B
3. C
4. D
A A A
BC
D D
