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The First Law of Thermodynamics
• According to the first law of thermodynamics,
the energy of the universe is constant:
– Energy can be transferred and
transformed, but
it cannot be created or destroyed
• The first law is also called the principle of
conservation of energy
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The Second Law of Thermodynamics
 During every energy transfer or transformation,
some energy is unusable, and is often lost as
heat
 According to the second law of
thermodynamics:
– Every energy transfer or transformation increases
the entropy (disorder) of the universe
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 8-6
Free energy
Reactants
Energy
Products
Amount of
energy
released
(∆G < 0)
Progress of the reaction
(a) Exergonic reaction: energy released
Free energy
Products
Energy
Reactants
Amount of
energy
required
(∆G > 0)
Progress of the reaction
(b) Endergonic reaction: energy required
Fig. 8-8
Adenine
Phosphate groups
Ribose
Fig. 8-9
P
P
P
Adenosine triphosphate (ATP)
H2O
Pi
+
Inorganic phosphate
P
P
+
Adenosine diphosphate (ADP)
Energy
Fig. 8-10
NH2
Glu
Glutamic
acid
NH3
+
Glu
∆G = +3.4 kcal/mol
Glutamine
Ammonia
(a) Endergonic reaction
1 ATP phosphorylates
glutamic acid,
making the amino
acid less stable.
P
+
Glu
ATP
Glu
+ ADP
NH2
2 Ammonia displaces
the phosphate group,
forming glutamine.
P
Glu
+
NH3
Glu
+ Pi
(b) Coupled with ATP hydrolysis, an exergonic reaction
(c) Overall free-energy change
Fig. 8-12
ATP + H2O
Energy from
catabolism (exergonic,
energy-releasing
processes)
ADP + P i
Energy for cellular
work (endergonic,
energy-consuming
processes)
Fig. 9-6-3
Electrons carried
via NADH and
FADH2
Electrons
carried
via NADH
Citric
acid
cycle
Glycolysis
Pyruvate
Glucose
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
Mitochondrion
Cytosol
ATP
ATP
ATP
Substrate-level
phosphorylation
Substrate-level
phosphorylation
Oxidative
phosphorylation
• Oxidative phosphorylation accounts for almost
90% of the ATP generated by cellular respiration
• A smaller amount of ATP is formed in glycolysis
and the citric acid cycle by substrate-level
phosphorylation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 9-7
Enzyme
Enzyme
ADP
P
Substrate
+
Product
ATP
Fig. 9-8
Energy investment phase
Glucose
2 ADP + 2
P
2 ATP
used
P
4 ATP
formed
Energy payoff phase
4 ADP + 4
2 NAD+ + 4 e– + 4 H+
2 NADH
+ 2 H+
2 Pyruvate + 2 H2O
Net
Glucose
4 ATP formed – 2 ATP used
2 NAD+ + 4 e– + 4 H+
2 Pyruvate + 2 H2O
2 ATP
2 NADH + 2 H+
Fig. 9-10
CYTOSOL
MITOCHONDRION
NAD+
NADH
+ H+
2
1
Pyruvate
Transport protein
3
CO2
Coenzyme A
Acetyl CoA
Fig. 9-11
Pyruvate
CO2
NAD+
CoA
NADH
+ H+
Acetyl CoA
CoA
CoA
Citric
acid
cycle
2 CO2
FADH2
3 NAD+
3 NADH
FAD
+ 3 H+
ADP + P
ATP
i
Fig. 9-13
NADH
50
2 e–
NAD+
FADH2
2 e–
40

FMN
FAD
Multiprotein
complexes
FAD
Fe•S 
Fe•S
Q

Cyt b
30
Fe•S
Cyt c1
I
V
Cyt c
Cyt a
Cyt a3
20
10
0
2 e–
(from NADH
or FADH2)
2 H+ + 1/2
O2
H2O
Fig. 9-14
INTERMEMBRANE SPACE
H+
Stator
Rotor
Internal
rod
Catalytic
knob
ADP
+
P
i
ATP
MITOCHONDRIAL MATRIX
Fig. 9-16
H+
H+
H+
H+
Protein complex
of electron
carriers
Cyt c
V
Q



FADH2
NADH
ATP
synthase
FAD
2 H+ + 1/2O2
NAD+
H2O
ADP + P i
(carrying electrons
from food)
ATP
H+
1 Electron transport chain
Oxidative phosphorylation
2 Chemiosmosis
Fig. 9-17
Electron shuttles
span membrane
CYTOSOL
2 NADH
6 NADH
2 NADH
Glycolysis
2
Pyruvate
Glucose
MITOCHONDRION
2 NADH
or
2 FADH2
2
Acetyl
CoA
+ 2 ATP
Maximum per glucose:
2 FADH2
Citric
acid
cycle
Oxidative
phosphorylation:
electron transport
and
chemiosmosis
+ 2 ATP
+ about 32 or 34 ATP
About
36 or 38 ATP
Fig. 9-18a
2 ADP + 2 P
Glucose
i
2 ATP
Glycolysis
2 Pyruvate
2 NAD+
2 Ethanol
(a) Alcohol fermentation
2 NADH
+ 2 H+
2 CO2
2 Acetaldehyde
Fig. 9-18b
2 ADP + 2
Glucose
P
i
2 ATP
Glycolysis
2 NAD+
2 Lactate
(b) Lactic acid fermentation
2 NADH
+ 2 H+
2 Pyruvate
Fig. 9-19
Glucose
CYTOSOL
Glycolysis
Pyruvate
No O2 present:
Fermentation
O2 present:
Aerobic cellular
respiration
MITOCHONDRION
Ethanol
or
lactate
Acetyl CoA
Citric
acid
cycle
Fig. 9-20
Proteins
Carbohydrates
Amino
acids
Sugars
Fats
Glycerol
Glycolysis
Glucose
Glyceraldehyde-3-
NH3
P
Pyruvate
Acetyl CoA
Citric
acid
cycle
Oxidative
phosphorylation
Fatty
acids
Fig. 10-3
Leaf cross section
Vein
Mesophyll
Stomata
Chloroplast
CO2
O2
Mesophyll cell
Outer
membrane
Thylakoid
Stroma
Granum
Thylakoid
space
Intermembrane
space
Inner
membrane
1 µm
5 µm
Fig. 10-4
Reactants:
Products:
12 H2O
6 CO2
C6H12O6
6 H2O
6 O2
Fig. 10-5-4
CO2
H2O
Light
NADP+
ADP
+ P
i
Light
Reactions
Calvin
Cycle
ATP
NADPH
Chloroplast
O2
[CH2O]
(sugar)
Fig. 10-7
Light
Reflected
light
Chloroplast
Absorbed
light
Granum
Transmitted
light
Fig. 10-9
RESULTS
Chlorophyll a
Chlorophyll b
Carotenoids
(a) Absorption spectra
400
500
600
700
Wavelength of light (nm)
(b) Action spectrum
Aerobic bacteria
Filament
of alga
(c) Engelmann’s
experiment
400
500
600
700
Fig. 10-13-5
4
Primary
acceptor
2 H+
+
1/ O
2
2
e–
H2O
Primary
acceptor
2
Fd
e–
Pq
7
e–
Cytochrome
complex
8
e–
NADP+
reductase
3
Pc
e–
e–
P700
5
P680
Light
1 Light
6
ATP
Pigment
molecules
Photosystem II
(PS II)
Photosystem I
(PS I)
NADP+
+ H+
NADPH
Fig. 10-15
Primary
acceptor
Primary
acceptor
Fd
Fd
Pq
NADP+
reductase
Cytochrome
complex
NADPH
Pc
Photosystem I
Photosystem II
ATP
NADP+
+ H+
Fig. 10-16
Mitochondrion
Chloroplast
MITOCHONDRION
STRUCTURE
CHLOROPLAST
STRUCTURE
H+
Intermembrane
space
Inner
membrane
Diffusion
Electron
transport
chain
Thylakoid
space
Thylakoid
membrane
ATP
synthase
Stroma
Matrix
Key
ADP + P
[H+]
Higher
Lower [H+]
i
H+
ATP
Fig. 10-17
STROMA
(low H+ concentration)
Cytochrome
complex
Photosystem II
4 H+
Light
Photosystem I
Light
Fd
NADP+
reductase
H2O
THYLAKOID SPACE
(high H+ concentration)
1
e–
Pc
2
1/
2
NADP+ + H+
NADPH
Pq
e–
3
O2
+2 H+
4 H+
To
Calvin
Cycle
Thylakoid
membrane
STROMA
(low H+ concentration)
ATP
synthase
ADP
+
Pi
ATP
H+
Fig. 10-18-3
Input
3
CO2
(Entering one
at a time)
Phase 1: Carbon fixation
Rubisco
3 P
Short-lived
intermediate
3 P
Ribulose bisphosphate
(RuBP)
P
6
P
3-Phosphoglycerate
P
6
ATP
6 ADP
3 ADP
3
Calvin
Cycle
6 P
P
1,3-Bisphosphoglycerate
ATP
6 NADPH
Phase 3:
Regeneration of
the CO2 acceptor
(RuBP)
6 NADP+
6 Pi
P
5
G3P
6
P
Glyceraldehyde-3-phosphate
(G3P)
1
Output
P
G3P
(a sugar)
Glucose and
other organic
compounds
Phase 2:
Reduction
Fig. 10-19
The C4 pathway
C4 leaf anatomy
Photosynthetic
cells of C4
plant leaf
Mesophyll
cell
Mesophyll cell
CO2
PEP carboxylase
Bundlesheath
cell
Oxaloacetate (4C)
Vein
(vascular tissue)
PEP (3C)
ADP
Malate (4C)
Stoma
Bundlesheath
cell
ATP
Pyruvate (3C)
CO2
Calvin
Cycle
Sugar
Vascular
tissue
Fig. 10-20
Sugarcane
Pineapple
C4
CAM
CO2
Mesophyll
cell
Bundlesheath
cell
Organic acid
CO2
1 CO2 incorporated
into four-carbon
organic acids
(carbon fixation)
CO2
Calvin
Cycle
Night
Organic acid
CO2
2 Organic acids
release CO2 to
Calvin cycle
Day
Calvin
Cycle
Sugar
Sugar
(a) Spatial separation of steps
(b) Temporal separation of steps