1. Energy Harvesting and Usage
Photosynthesis and Cellular Respiration

2. What you must know
Photosynthesis
Respiration
Products and reactants for each stage
Light Dependent
Photosystem II
Photosystem I
Light Independent (Calvin Cycle)
Where each stage occurs
CAM versus C4 strategies for plants
Chlorophyll a, b, and carotenoids
Products, reactants, location, and order of processes
Glycolysis
Kreb (Citric Acid) Cycle
Electron Transport Chain
Fermentation
Number of ATP produced

3. Must Knows – cont. Overall Photosynthesis Overall Respiration Rubisco
Proteins and Molecules
Equations
Rubisco
RuBP
ATP Synthase
Co-enzyme A
ATP, ADP, AMP
NADH
FADH2
NADPH
Overall Photosynthesis Overall Respiration

4. A typical mesophyll cell has 30–40 chloroplasts
Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf
A typical mesophyll cell has 30–40 chloroplasts
The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast); thylakoids may be stacked in columns called grana
Chloroplasts also contain stroma, a dense fluid
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

5. Chloroplast Outer membrane Thylakoid Intermembrane space Stroma Granum
Fig. 10-3b
Chloroplast
Outer
membrane
Thylakoid
Intermembrane
space
Stroma
Granum
Thylakoid
space
Inner
membrane
Figure 10.3 Zooming in on the location of photosynthesis in a plant
1 µm

6. Tracking Atoms Through Photosynthesis: Scientific Inquiry
Photosynthesis can be summarized as the following equation:
6 CO H2O + Light energy  C6H12O6 + 6 O2 + 6 H2O
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7. The Two Stages of Photosynthesis: A Preview
Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part)
The light reactions (in the thylakoids):
Split H2O
Release O2
Reduce NADP+ to NADPH
Generate ATP from ADP by photophosphorylation
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

8. The Calvin cycle (in the stroma) forms sugar from CO2, using ATP and NADPH
The Calvin cycle begins with carbon fixation, incorporating CO2 into organic molecules
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

9. i Light NADP+ ADP Light Reactions Chloroplast H2O + P Fig. 10-5-1
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
Chloroplast

10. i Light NADP+ ADP Light Reactions ATP NADPH Chloroplast O2 H2O + P
Fig
H2O
Light
NADP+
ADP + P i
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast O2

11. i CO2 Light NADP+ ADP Calvin Cycle Light Reactions ATP NADPH
Fig
H2O
CO2
Light
NADP+
ADP + P i
Calvin
Cycle
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast O2

12. i CO2 Light NADP+ ADP Calvin Cycle Light Reactions ATP NADPH
Fig
H2O
CO2
Light
NADP+
ADP + P i
Calvin
Cycle
Light
Reactions
ATP
Figure 10.5 An overview of photosynthesis: cooperation of the light reactions and the Calvin cycle
NADPH
Chloroplast
[CH2O]
(sugar) O2

13. Electron transport chain
Fig
H2O
CO2
Light
NADP+
ADP + P i
Light
Reactions:
Photosystem II
Electron transport chain
Photosystem I
RuBP
3-Phosphoglycerate
Calvin
Cycle
ATP
G3P
Figure A review of photosynthesis
Starch
(storage)
NADPH
Chloroplast O2
Sucrose (export)

14. Chlorophyll a is the main photosynthetic pigment
Accessory pigments, such as chlorophyll b, broaden the spectrum used for photosynthesis
Accessory pigments called carotenoids absorb excessive light that would damage chlorophyll
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15. RESULTS Fig. 10-9 Chloro- Chlorophyll b Absorption of light by
phyll a
Chlorophyll b
Absorption of light by
chloroplast pigments
Carotenoids
(a) Absorption spectra
400
500
600
700
Wavelength of light (nm)
(measured by O2 release)
Rate of photosynthesis
Figure 10.9 Which wavelengths of light are most effective in driving photosynthesis?
(b) Action spectrum
Aerobic bacteria
Filament
of alga
(c) Engelmann’s
experiment
400
500
600
700

16. There are two types of photosystems in the thylakoid membrane
Photosystem II (PS II) functions first (the numbers reflect order of discovery) and is best at absorbing a wavelength of 680 nm
The reaction-center chlorophyll a of PS II is called P680
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

17. Photosystem I (PS I) is best at absorbing a wavelength of 700 nm
The reaction-center chlorophyll a of PS I is called P700
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

18. O2 is released as a by-product of this reaction
P680+ (P680 that is missing an electron) is a very strong oxidizing agent
H2O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680
O2 is released as a by-product of this reaction
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

19. Calvin Cycle Regenerates starting material
Builds sugar from smaller molecules using ATP and NADPH
3 Phases
Carbon fixation (uses rubisco)
Reduction
Regneration of the CO2 acceptor (RuBP)

20. CAM plants Photosynthetic adaptation to arid conditions
Plants open stomata during the night and close during the day (reverse of other plants)

21. C4 Plants Plants that have an additional step before the Calvin cycle
Incorporate CO2 in four-carbon compounds in mesophyll cells

22. Glycolysis Occurs in the cytoplasm Anaerobic reaction Requires 2 ATP
Produces 4 ATP, 2 NADH, and 2 Pyruvate

23. Kreb Cycle (aka citric acid cycle)
Aerobic process
Occurs in mitochondria (matrix)
Each turn of the cycle generates
1 ATP
3 NADH
1 FADH2
For each glucose molecule, there are 2 turns
(total of 2 ATP, 6 NADH, and 2 FADH2)

24. Electron Transport Chain
NADH and FADH2 are electron carriers which donate electrons to the chain which causes the formation of ATP
Aerobic Process
Cristae of mitochondria and intermembrane space
Creates H2O
Creates about 32 ATP
Uses H+ gradient to drive ATP synthesis

25. Fig. 10-UN5

26. i INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob
Fig. 9-14
INTERMEMBRANE SPACE H+
Stator
Rotor
Internal
rod
Figure 9.14 ATP synthase, a molecular mill
Cata-
lytic
knob
ADP + P
ATP i
MITOCHONDRIAL MATRIX

27. Fermentation
Glycolysis plus regeneration of NAD+ (for reuse in glycolysis)
Occurs in Cytoplasm
Anaerobic respiration
Two types
Alcohol
Lactic acid
Does not generate any ATP just electron carrier proteins