1. C4 versus C3 plants

2. cyclic production of intermediate sugar phosphates
Fig. 10-9, p. 157
(CO2 from the air)
stroma
Carbon dioxide
fixation
(intermediates)
(PGA)
(RuBP)
rubisco
H2O
ADP Pi
NADP+
(PGAL)
cyclic production of intermediate sugar phosphates
Calvin cycle
sugar phosphate synthesis
typically used at once to form carbohydrates (mainly
sucrose, starch, cellulose)
sugar phosphate
Using ATP and NADPH to generate high energy containing covalent bonds
PGA: phosphoglyceric acid
PGAL: phosphoglyceraldehyde H H P C C OH
PGA H C O
Low energy electrons
O H
ATP + NADPH
Figure 10.9: Some major steps in the C3 pathway of photosynthesis. Carbon dioxide enters the cycle when the enzyme rubisco combines CO2 with ribulose bisphosphate (RuBP) to produce two molecules of phosphoglyceric acid (PGA). Carbon atoms of the key molecules are shown in red. All of the intermediates have one or two phosphate groups attached. For simplicity, only the phosphates on the resulting sugar phosphate are shown. ADP, Adenosine diphosphate; ATP, adenosine triphosphate; PGAL, phosphoglyceraldehyde; Pi, inorganic phosphate. H H P C C OH
PGAL H C O
High energy electrons H

3. The C4 pathway concentrates CO2
Interaction between the C4 cycle and the C3 cycle
C4 cycle
AMP
mesophyll cells
Figure 10.12: Interaction between the C4 cycle in mesophyll cells and the C3 cycle in bundle sheath cells.
C3 cycle
bundle sheath cells
Fig , p. 159

4. The C4 pathway concentrates CO2
air
space
bundle
sheath cell
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.
Figure 10.11: Photosynthesis in corn (Zea mays). A section through a leaf shows the concentric arrangement of bundle sheath and mesophyll cells. Compare this diagram with Figure 6.10a.
CO2 movement
mesophyll cells
guard
cell
vascular bundle
lower
epidermis
Fig , p. 159

5. Where/when is it used/made?

6. Overall Photosynthesis Reaction
6CO2 + 6H2O + energy  C6H12O6 + 6O2
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 6

7. Light-independent reactions
oxygen released
sunlight energy
photosystem II e− H+
electron transport system
H2O is split
Light-dependent reactions H+
lumen
(H+ reservoir) H+
photosystem I e−
electron transport system
NADP+
carbon dioxide used
Figure 10.3: Diagram of a section of chloroplast granum showing where reactions take place. ADP, Adenosine diphosphate.
ADP + Pi H+ H+
Light-independent reactions
sugar phosphate
Stroma
carbohydrate end product (e.g. sucrose, starch, cellulose)
Fig. 10-3, p. 151

8. 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 8

9. Electron transport chain
Cytoplasm
Overview of respiration steps
glucose
energy
Input(ATP)
Glycolysis 2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
TCA
Cycle
4 CO2
6 NADH
2 FADH2 2
ATP
Figure 9.5: Overview of the complete oxidation of glucose during aerobic respiration. ATP, Adenosine triphosphate; TCA, tricarboxylic acid.
water
Electron transport chain
phosphorylation 34
ATP
oxygen
Mitochondrion
Fig. 9-5, p. 138

10. TCA cycle INTERMEMBRANE space MATRIX
pyruvate from cytoplasm
inner membrane H+
electron transport system
Coenzymes give up electrons, hydrogen (H+) to transport system e−
NADH
acetyl-CoA e−
NADH H+
TCA cycle H+
FADH2
As electrons pass through system, H+ is pumped out from matrix e−
carbon dioxide
Oxygen accepts electrons, joins with 2H+, forms water
ATP
synthesized 2
ATP
Figure 9.8c: Detail of membranes, showing location of electron transport system and adenosine triphosphate (ATP) synthesis. Pi
ADP
oxygen H+
INTERMEMBRANE
space H+
MATRIX
H+ flows in H+ H+
Fig. 9-8c, p. 142

11. Comparison

12. 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

13. What is needed to proceed ?

14. Electron transport chain
Cytoplasm
Overview of respiration steps
glucose
energy
Input(ATP)
Glycolysis 2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
TCA
Cycle
4 CO2
6 NADH
2 FADH2 2
ATP
Figure 9.5: Overview of the complete oxidation of glucose during aerobic respiration. ATP, Adenosine triphosphate; TCA, tricarboxylic acid.
water
Electron transport chain
phosphorylation 34
ATP
oxygen
Mitochondrion
Fig. 9-5, p. 138

15. General overview: Making ATP from starch
Electron transport system
STARCH (Glucose multimer)
Digestion
6 O H+
Glucose (6C)
NAD+
+ 2 FAD
+ 12 H2O + H+ gradient
2 ADP + 2 iP + 2 NAD+
Glycolysis
2 Pyruvate (3C) +2 ATP + 2 NADH
CoASH + 2 NAD+
Chemiosmosis
Entry into TCA
2 Acetyl-CoA (2C) + 2 CO2 + 2 NADH
34 ADP + 34 iP
2 ADP + 2 iP + 6 NAD+
+ 2FAD + 6 H2O
TCA
6X3 + 2X3 + 2X3
+ 2X2
ATP
2 (2CO2 + ATP + 3NADH + FADH2)

16. NONCYCLIC ELECTRON TRANSPORT
Fig. 10-7, p. 154
NONCYCLIC ELECTRON TRANSPORT
P700* e−
-0.6
sunlight
energy
Electron Transport System
NADPH
P680* e− e−
potential to transfer electrons (measured in volts)
H+ + NADP+
sunlight
energy
ADP + Pi
electron transport system e− e−
P700
+0.4
Pigments from the light harvesting complex
photosystem I
released energy used to form ATP
from ADP and phosphate
+0.8
Figure 10.7: The pathway of noncyclic electron transport from water to reduced nicotinamide adenine dinucleotide phosphate (NADPH), with the associated adenosine triphosphate (ATP) synthesis. Pi, Inorganic phosphate.
photosystem II e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I

17. CYCLIC ELECTRON TRANSPORT
Fig. 10-7, p. 154
potential to transfer electrons (measured in volts)
+0.8
+0.4
-0.6
CYCLIC ELECTRON TRANSPORT
P700* e−
sunlight
energy
Electron Transport System
NADPH
P680* e− e−
H+ + NADP+
sunlight
energy
ADP + Pi
electron transport system e− e−
P700
photosystem I
released energy used to form ATP
from ADP and phosphate
photosystem II
Figure 10.7: The pathway of noncyclic electron transport from water to reduced nicotinamide adenine dinucleotide phosphate (NADPH), with the associated adenosine triphosphate (ATP) synthesis. Pi, Inorganic phosphate. e−
H2O
photolysis

18. cyclic production of intermediate sugar phosphates
Fig. 10-9, p. 157
(CO2 from the air)
stroma
Carbon dioxide
fixation
(intermediates)
(PGA)
(RuBP)
rubisco
H2O
ADP Pi
NADP+
(PGAL)
cyclic production of intermediate sugar phosphates
Calvin cycle
sugar phosphate synthesis
typically used at once to form carbohydrates (mainly
sucrose, starch, cellulose)
sugar phosphate
Using ATP and NADPH to generate high energy containing covalent bonds
PGA: phosphoglyceric acid
PGAL: phosphoglyceraldehyde H H P C C OH
PGA H C O
Low energy electrons
O H
ATP + NADPH
Figure 10.9: Some major steps in the C3 pathway of photosynthesis. Carbon dioxide enters the cycle when the enzyme rubisco combines CO2 with ribulose bisphosphate (RuBP) to produce two molecules of phosphoglyceric acid (PGA). Carbon atoms of the key molecules are shown in red. All of the intermediates have one or two phosphate groups attached. For simplicity, only the phosphates on the resulting sugar phosphate are shown. ADP, Adenosine diphosphate; ATP, adenosine triphosphate; PGAL, phosphoglyceraldehyde; Pi, inorganic phosphate. H H P C C OH
PGAL H C O
High energy electrons H

19. What is (are) the final result (s)?

20. Electron transport chain
Cytoplasm
Overview of respiration steps
glucose
energy
Input(ATP)
Glycolysis 2
ATP
(net)
2 NADH
2 pyruvate
2 CO2
2 NADH
TCA
Cycle
4 CO2
6 NADH
2 FADH2 2
ATP
Figure 9.5: Overview of the complete oxidation of glucose during aerobic respiration. ATP, Adenosine triphosphate; TCA, tricarboxylic acid.
water
Electron transport chain
phosphorylation 34
ATP
oxygen
Mitochondrion
Fig. 9-5, p. 138

21. NONCYCLIC ELECTRON TRANSPORT
Fig. 10-7, p. 154
NONCYCLIC ELECTRON TRANSPORT
P700* e−
-0.6
sunlight
energy
Electron Transport System
NADPH
P680* e− e−
potential to transfer electrons (measured in volts)
H+ + NADP+
sunlight
energy
ADP + Pi
electron transport system e− e−
P700
+0.4
Pigments from the light harvesting complex
photosystem I
released energy used to form ATP
from ADP and phosphate
+0.8
Figure 10.7: The pathway of noncyclic electron transport from water to reduced nicotinamide adenine dinucleotide phosphate (NADPH), with the associated adenosine triphosphate (ATP) synthesis. Pi, Inorganic phosphate.
photosystem II e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I

22. CYCLIC ELECTRON TRANSPORT
Fig. 10-7, p. 154
potential to transfer electrons (measured in volts)
+0.8
+0.4
-0.6
CYCLIC ELECTRON TRANSPORT
P700* e−
sunlight
energy
Electron Transport System
NADPH
P680* e− e−
H+ + NADP+
sunlight
energy
ADP + Pi
electron transport system e− e−
P700
photosystem I
released energy used to form ATP
from ADP and phosphate
photosystem II
Figure 10.7: The pathway of noncyclic electron transport from water to reduced nicotinamide adenine dinucleotide phosphate (NADPH), with the associated adenosine triphosphate (ATP) synthesis. Pi, Inorganic phosphate. e−
H2O
photolysis

23. Division of Labor in Chloroplasts
Green thylakoids
Capture light
Liberate O2 from H2O
Form ATP from ADP and phosphate
Reduce NADP+ to NADPH
Light reactions
Colorless stroma
Contains water-soluble enzymes
Captures CO2
Uses energy from ATP and NADPH for sugar synthesis
Dark reactions

24. Where/when are energy carriers (ATP, NADH and NADPH) needed and where/when are they produced?

25. Final electron acceptors?
Electron donors
&
Final electron acceptors?

26. TCA cycle INTERMEMBRANE space MATRIX
pyruvate from cytoplasm
inner membrane H+
electron transport system
Coenzymes give up electrons, hydrogen (H+) to transport system e−
NADH
acetyl-CoA e−
NADH H+
TCA cycle H+
FADH2
As electrons pass through system, H+ is pumped out from matrix e−
carbon dioxide
Oxygen accepts electrons, joins with 2H+, forms water
ATP
synthesized 2
ATP
Figure 9.8c: Detail of membranes, showing location of electron transport system and adenosine triphosphate (ATP) synthesis. Pi
ADP
oxygen H+
INTERMEMBRANE
space H+
MATRIX
H+ flows in H+ H+
Fig. 9-8c, p. 142

27. NONCYCLIC ELECTRON TRANSPORT
Fig. 10-7, p. 154
NONCYCLIC ELECTRON TRANSPORT
P700* e−
-0.6
sunlight
energy
Electron Transport System
NADPH
P680* e− e−
potential to transfer electrons (measured in volts)
H+ + NADP+
sunlight
energy
ADP + Pi
electron transport system e− e−
P700
+0.4
Pigments from the light harvesting complex
photosystem I
released energy used to form ATP
from ADP and phosphate
+0.8
Figure 10.7: The pathway of noncyclic electron transport from water to reduced nicotinamide adenine dinucleotide phosphate (NADPH), with the associated adenosine triphosphate (ATP) synthesis. Pi, Inorganic phosphate.
photosystem II e−
H2O
photolysis
P680: reaction center of photosystem II
P700: reaction center of photosystem I

28. Other (very) important things…

29. Absorption spectra of Chlorophyll a and b
100 80
chlorophyll b
Percent of light absorbed 60 40
chlorophyll a
Figure 10.5: Absorption spectra of chlorophylls a and b at different wavelengths of light. Graph shows the fraction of received light that is absorbed when the pigment is exposed to various wavelengths of light. The relation between wavelength and color is also shown. 20
400
500
600
700
Wavelength (nm)
Fig. 10-5, p. 152

30. Twelve Most Common Elements in Living Organisms
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