Transcript Enzymes PPT #1 - Mayfield City Schools

Ch. 6.3 Enzymes
Review Energy & Reactions
Exergonic reaction This reaction releases energy
 Can be
spontaneous
Reactant
 Has more useable energy
Products
 Have less useable energy
Both reactions require energy to start =
Activation Energy
Endergonic reaction Energy absorbed  Cannot be
spontaneous
Reactants
 Have less useable energy
Product
 Has more useable energy
Activation
Initial
energy
Investment
Initial
Investment
More
Spent
work
more
than
than fun
received
is received
Money
Fun is released
Energy
in
spent
Moneyisisput
Work
Graphs of Energy Change
More
Received
fun
than
more
than
work
spent
BadTime
Investment
for reaction
Good Investment
By Enzymes
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 =
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
A.A.
A.A.
A.A.
A.A.
A.A.
denaturation
(unfolding)

Polar A.A.
NonPolar A.A.
Polar A.A.
If denatures (unfolds), then loses shape and
loses function (loses site to bind)



Animations
http://highered.mcgrawhill.com/classware/ala.do?isbn=0072986670&alaid=ala_1048056&show
SelfStudyTree=true
http://highered.mcgrawhill.com/classware/ala.do?isbn=0072986670&alaid=ala_1048054&show
SelfStudyTree=true
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
13%
0%
ta
l
ca
sit
Ac
t iv
e
ys
ts
es
0%
s
D.
te
C.
88%
Su
bs
tra
B.
proteins
Substrates
Active sites
catalysts
pr
ot
ei
ns
A.
The place where a substrate
and an enzyme meet is called
the
100%
Ps it
e
sit
e
0%
Ac
t iv
e
sit
e
0%
ys
t
al
Ca
t
pl
ex
co
m
D.
0%
te
C.
su
bs
tra
B.
Enzymesubstrate
complex
Catalyst site
Active site
P-site
En
zy
m
e-
A.
When enzyme changes its
shape to better fit its
substrate this is called
100%
0%
n
tio
re
ac
ed
ic
lo
st
er
ac
re
yz
ed
In
du
c
tio
n
fit
0%
fit
0%
An
al
ta
l
D.
ca
C.
A
B.
Active fit
A catalyzed
reaction
Induced fit
An allosteric
reaction
Ac
t iv
e
A.
The energy needed to start a
chemical reaction is called
er
gy
Al
lo
st
er
ic
En
En
e
Ac
t iv
at
io
n
en
ic
rm
Ex
ot
he
0%
rg
y
er
gy
0%
y
en
er
g
D.
0%
ic
C.
100%
th
er
m
B.
Endothermic
energy
Exothermic
energy
Activation
Energy
Allosteric Energy
En
do
A.
Which shape is the enzyme?
D
D
A
C
A
B
87%
A
13%
0%
0%
D
4.
C
3.
B
2.
A
B
C
D
A
1.
Which shape is the active site?
D
D
A
C
A
88%
B
A
6%
6%
0%
D
4.
C
3.
B
2.
A
B
C
D
A
1.
Which shape is the product?
100%
D
D
A
C
A
B
A
0%
0%
0%
D
4.
C
3.
B
2.
A
B
C
D
A
1.