Download H 2 O

C4 versus C3 plants
Using ATP and NADPH to generate high
energy containing covalent bonds
PGA: phosphoglyceric acid
PGAL: phosphoglyceraldehyde
(CO2 from the air)
stroma
H 2O
Carbon dioxide
fixation
rubisco
P
H
H
C
C
OH
H
C
O
(RuBP) (intermediates)
(PGA)
ADP
O
cyclic production of
intermediate sugar phosphates
ATP + NADPH
ADP
Pi
NADP+
(PGAL)
Pi
(PGAL)
sugar phosphate synthesis
sugar phosphate
Low energy electrons
H
Calvin
cycle
PGA
typically used at once to form
carbohydrates (mainly
sucrose, starch, cellulose)
Fig. 10-9, p. 157
P
H
H
C
C
OH
PGAL
H
C
H
O
High energy electrons
The C4 pathway concentrates CO2
C4 cycle
Interaction between the C4 cycle
and the C3 cycle
AMP
mesophyll cells
C3 cycle
bundle sheath cells
Fig. 10-12, p. 159
The C4 pathway concentrates CO2
air
space
guard
cell
bundle
sheath cell
CO2 movement
upper
epidermis
In C4 plants, CO2 is first
captured by PEP
carboxylase in mesophyll
cells to make oxaloacetate
which is subsequently
turned into malate. This
malate then diffuses into the
chloroplasts of bundle
sheath cells where it
releases CO2. Thus, bundle
sheath chloroplasts contain
higher CO2 concentrations
compared to chloroplasts in
mesophyll cells and
therefore have higher
photosynthesis and lower
photorespiration rates.
mesophyll cells
vascular bundle
lower
epidermis
Fig. 10-11, p. 159
Where/when is it
used/made?
Overall Photosynthesis
Reaction
6CO2 + 6H2O + energy  C6H12O6 + 6O2
24 C-O bonds
+
12 H-O bonds
36 covalent bonds
7 C-O bonds
+
5 C-C bonds
+
7 C-H bonds
+
5 H-O bonds
+
12 O-O bonds
36 covalent bonds
oxygen released
sunlight
energy
photosystem
II
e−
H+
H2O is split
H+
lumen
(H+ reservoir)
H+
NADP+
H+
electron
transport
system
H+
Stroma
Lightdependent
reactions
photosystem
I
e−
ADP + Pi
electron
transport
system
sugar
phosphate
carbon
dioxide
used
Lightindependent
reactions
carbohydrate end product (e.g. sucrose, starch, cellulose)
Fig. 10-3, p. 151
Overall Respiration Reaction
C6H12O6 + 6O2  6CO2 + 6H2O + energy
7 C-O bonds
+
5 C-C bonds
+
7 C-H bonds
+
5 H-O bonds
+
12 O-O bonds
36 covalent bonds
24 C-O bonds
+
12 H-O bonds
36 covalent bonds
Cytoplasm
energy
Input(ATP)
Overview of
respiration
steps
glucose
Glycolysis
2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
6 NADH
2 FADH2
TCA
Cycle
4 CO2
2
ATP
water
Electron transport chain
phosphorylation
Mitochondrion
34
ATP
oxygen
Fig. 9-5, p. 138
pyruvate from cytoplasm
inner membrane
H+
Coenzymes
give up
electrons,
hydrogen (H+)
to transport
system
NADH
acetyl-CoA
NADH
TCA
cycle
e−
e−
H+
H+
FADH2
As electrons pass
through system,
H+ is pumped out
from matrix
carbon dioxide
2
ATP
Pi
ADP
ATP
synthesized
e−
Oxygen accepts
electrons, joins with
2H+, forms water
oxygen
H+
H+
MATRIX
electron
transport
system
H+
H+ flows in
H+
INTERMEMBRANE
space
Fig. 9-8c, p. 142
Comparison
Chloroplasts and mitochondria
• In common:
- membrane localized ATP synthase
- H+ concentration difference
- electron transport chain
- DNA
- Bacterial origin
• Differences:
–
–
–
–
–
NADH versus NADPH
One versus two outer membranes
O2 production versus consumption
CO2 consumption versus production
Production of energy carriers to promote uphill reactions in
general
– Production of energy carriers to allow C-C and C-H bond
formation
What is needed to
proceed ?
Cytoplasm
energy
Input(ATP)
Overview of
respiration
steps
glucose
Glycolysis
2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
6 NADH
2 FADH2
TCA
Cycle
4 CO2
2
ATP
water
Electron transport chain
phosphorylation
Mitochondrion
34
ATP
oxygen
Fig. 9-5, p. 138
General overview: Making
ATP from starch
Electron transport system
STARCH (Glucose multimer)
6 O2 + 24 H+
Digestion
Glucose (6C)
Glycolysis
2 ADP + 2 iP + 2 NAD+
6 + 2 + 2 NAD+
+ 2 FAD
+ 12 H2O + H+ gradient
2 Pyruvate (3C) +2 ATP + 2 NADH
Entry into TCA
CoASH + 2 NAD+
2 Acetyl-CoA (2C) + 2 CO2 + 2 NADH
TCA
2 ADP + 2 iP + 6 NAD+
+ 2FAD + 6 H2O
2 (2CO2 + ATP + 3NADH + FADH2)
Chemiosmosis
34 ADP + 34 iP
6X3 + 2X3 + 2X3
+ 2X2
34
ATP
potential to transfer electrons (measured in volts)
NONCYCLIC ELECTRON TRANSPORT
P700*
-0.6
e−
sunlight
energy
P680*
e−
NADP
H
e−
0
sunlight
energy
e−
+0.4
H+ + NADP+
ADP + Pi
e−
P700
photosystem I
+0.8
photosystem
II
Pigments from the light
harvesting complex
released energy used to form
ATP
from ADP and phosphate
e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I
Fig. 10-7, p. 154
potential to transfer electrons (measured in vo
CYCLIC ELECTRON TRANSPORT
P700*
-0.6
e−
sunlight
energy
NADPH
P680*
e−
e−
0
sunlight
energy
e−
+0.
4
H+ + NADP+
ADP + Pi
e−
P700
photosystem I
+0.
8
photosystem
II
released energy used to form
ATP
from ADP and phosphate
e−
H2O
photolysis
Fig. 10-7, p. 154
Using ATP and NADPH to generate high
energy containing covalent bonds
PGA: phosphoglyceric acid
PGAL: phosphoglyceraldehyde
(CO2 from the air)
stroma
H 2O
Carbon dioxide
fixation
rubisco
P
H
H
C
C
OH
H
C
O
(RuBP) (intermediates)
(PGA)
ADP
O
cyclic production of
intermediate sugar phosphates
ATP + NADPH
ADP
Pi
NADP+
(PGAL)
Pi
(PGAL)
sugar phosphate synthesis
sugar phosphate
Low energy electrons
H
Calvin
cycle
PGA
typically used at once to form
carbohydrates (mainly
sucrose, starch, cellulose)
Fig. 10-9, p. 157
P
H
H
C
C
OH
PGAL
H
C
H
O
High energy electrons
What is (are) the
final result (s)?
Cytoplasm
energy
Input(ATP)
Overview of
respiration
steps
glucose
Glycolysis
2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
6 NADH
2 FADH2
TCA
Cycle
4 CO2
2
ATP
water
Electron transport chain
phosphorylation
Mitochondrion
34
ATP
oxygen
Fig. 9-5, p. 138
potential to transfer electrons (measured in volts)
NONCYCLIC ELECTRON TRANSPORT
P700*
-0.6
e−
sunlight
energy
P680*
e−
NADP
H
e−
0
sunlight
energy
e−
+0.4
H+ + NADP+
ADP + Pi
e−
P700
photosystem I
+0.8
photosystem
II
Pigments from the light
harvesting complex
released energy used to form
ATP
from ADP and phosphate
e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I
Fig. 10-7, p. 154
potential to transfer electrons (measured in vo
CYCLIC ELECTRON TRANSPORT
P700*
-0.6
e−
sunlight
energy
NADPH
P680*
e−
e−
0
sunlight
energy
e−
+0.
4
H+ + NADP+
ADP + Pi
e−
P700
photosystem I
+0.
8
photosystem
II
released energy used to form
ATP
from ADP and phosphate
e−
H2O
photolysis
Fig. 10-7, p. 154
Division of Labor in Chloroplasts
Green thylakoids
• Capture light
• Liberate O2 from H2O
• Form ATP from ADP and
phosphate
• Reduce NADP+ to NADPH
Colorless stroma
• Contains water-soluble enzymes
• Captures CO2
• Uses energy from ATP and
NADPH for sugar synthesis
Light reactions
Dark reactions
Where/when are energy
carriers (ATP, NADH and
NADPH) needed and
where/when are they
produced?
Electron donors
&
Final electron
acceptors?
pyruvate from cytoplasm
inner membrane
H+
Coenzymes
give up
electrons,
hydrogen (H+)
to transport
system
NADH
acetyl-CoA
NADH
TCA
cycle
e−
e−
H+
H+
FADH2
As electrons pass
through system,
H+ is pumped out
from matrix
carbon dioxide
2
ATP
Pi
ADP
ATP
synthesized
e−
Oxygen accepts
electrons, joins with
2H+, forms water
oxygen
H+
H+
MATRIX
electron
transport
system
H+
H+ flows in
H+
INTERMEMBRANE
space
Fig. 9-8c, p. 142
potential to transfer electrons (measured in volts)
NONCYCLIC ELECTRON TRANSPORT
P700*
-0.6
e−
sunlight
energy
P680*
e−
NADP
H
e−
0
sunlight
energy
e−
+0.4
H+ + NADP+
ADP + Pi
e−
P700
photosystem I
+0.8
photosystem
II
Pigments from the light
harvesting complex
released energy used to form
ATP
from ADP and phosphate
e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I
Fig. 10-7, p. 154
Other (very)
important things…
Absorption spectra of Chlorophyll a and b
Percent of light absorbed
100
80
chlorophyll b
60
chlorophyll a
40
20
0
400
500
600
Wavelength (nm)
700
Fig. 10-5, p. 152
Twelve Most Common Elements in
Living Organisms
Element
Symbol
Number of Protons
Hydrogen
H
1
Carbon
C
6
Nitrogen
N
7
Oxygen
O
8
Sodium
Na
11
Magnesium
Mg
12
Phosphorus
P
15
Sulfur
S
16
Chlorine
Cl
17
Potassium
K
19
Calcium
Ca
20
Iron
Fe
26