Chapter 8 Pictures
Potential and Kinetic Energy
2nd Law of Thermodynamics
Potential Energy-Fuel
Kinetic Energy
25% drives the pistons
75% lost as heat
*In every chemical reaction, some energy is lost as heat.
Theoretical metabolic pathway
Enzyme 1
A
Enzyme 3
D
C
B
Reaction 1
Starting
molecule
Enzyme 2
Reaction 2
Reaction 3
Product
Fig 5.2. Catabolic vs. Anabolic Reactions
• Condensation →
reactions (anabolic)
• Hydrolysis
reactions
(catabolic)
→
• Catabolic Rxns –
• O-O O + O + Energy
• Anabolic RxnsO + O + Energy
O-O
Figure 8.6
Fig 8.14 Energy Profile for a Catabolic (Exergonic)
Reaction
ALL rxns require
some input of energy
In exergonic rxns
∆G is a negative
number
Question 8.1
+ H2O
fructose +
glucose
Example 2: Sucrose hydrolysis
(very slow reaction)
Example 1: Baking soda
+ vinegar (fast reaction)
Examples of an exergonic and
endergonic reaction
+
Glutamic Acid
Glutamine
Ammonia
ΔG = - 3.4 kcal/mol
+
Glutamine
Ammonia
ΔG = + 3.4 kcal/mol
Glutamic Acid
Chemical Equilibrium
An organism in
metabolic equilibrium
Equilibrium
ATP
Metabolic Disequilibrium
Food
ATP
ATP
ATP
Waste Products
Fig 8.3
Chapter 8-ATP
ATP = Currency of the Cell
Fig 8.11
Fig 8.9 ATP hydrolysis
Fig 8.8
Coupled Reactions
Fig 8.10
ATP hydrolysis
ATP synthesis
Question 8.2
Chapter 8 - Enzymes
Fig 8.13. Enzyme-catalyzed
reaction: hydrolysis by sucrase
Metabolic
Map
Fig 8.13. Enzyme-catalyzed
reaction: hydrolysis by Sucrase
Fig 8.14
Energy
Profile
Energy (heat)
absorbed from
the surroundings
Energy (heat)
released by
the reaction
Course of
reaction
without
enzyme
EA
without
enzyme
EA with
enzyme
is lower
Free energy
Fig 8.15
Energy
Profile +/Enzyme
Reactants
∆G is unaffected
by enzyme
Course of
reaction
with enzyme
Products
Progress of the reaction
Fig
8.17
Fig 8.16
Fig 8.18a
Optimal temperature for
typical human enzyme
Optimal temperature for
enzyme of thermophilic
Rate of reaction
(heat-tolerant)
bacteria
0
20
40
Temperature (Cº)
(a) Optimal temperature for two enzymes
80
100
Fig 8.18b
Optimal pH for pepsin
(stomach enzyme)
Rate of reaction
Optimal pH
for trypsin
(intestinal
enzyme)
0
1
2
3
(b) Optimal pH for two enzymes
4
5
6
7
8
9
Question 8.3
A substrate can
bind normally to the
active site of an
enzyme.
Substrate
Active site
Fig 8.19
a, b
Enzyme
(a) Normal binding
A competitive
inhibitor mimics the
substrate, competing
for the active site.
Figure 8.19
Competitive
inhibitor
(b) Competitive inhibition
Fig 8.19c
A noncompetitive
inhibitor binds to the
enzyme away from
the active site, altering
the conformation of
the enzyme so that its
active site no longer
functions.
Noncompetitive inhibitor
Figure 8.19
(c) Noncompetitive inhibition
Fig 8.21
Question 8.4