1. PHOTOSYNTHESIS

2. Photosynthesis
An anabolic, endergonic, carbon dioxide (CO2) requiring process that uses light energy (photons) and water (H2O) to produce organic macromolecules (glucose).
6CO H2O  C6H12O O2
glucose
SUN
photons

3. In what types of organisms does photosynthesis take place?
Question:
In what types of organisms does photosynthesis take place?

4. In plants, bacteria, and protists

5. Photosynthesis Animations
Comprehensive Overview:
Cyclic and Noncyclic Photophosphorylation: Electron Transport Chain: Light Reactions: Photophosphorylation:
Proton Pumps:
Calvin Cycle: Calvin Cycle:

6. Plants Autotrophs: self-producers. Location: 1. Leaves a. stoma
b. mesophyll cells
Stoma
Mesophyll
Cell
Chloroplast

7. Stomata
Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere.
Oxygen
(O2)
Guard Cell
Carbon Dioxide
(CO2)

8. Stomata Regulate Gas Exchange8

9. Leaf Anatomy 9

10. Chloroplast Organelle where photosynthesis takes place. Stroma
Outer Membrane
Thylakoid
Granum
Inner Membrane

11. Contain thylakoids and grana
Chloroplasts
Contain thylakoids and grana
Chloroplast
Mesophyll
5 µm
Outer
membrane
Intermembrane
space
Inner
Thylakoid
Granum
Stroma
1 µm

12. Thylakoids
Thylakoid Membrane
Granum
Thylakoid Space

13. Mesophyll Cell
Nucleus
Cell Wall
Chloroplast
Central Vacuole

15. Question:
Why are plants green?

16. Chlorophyll Molecules
Located in the thylakoid membranes.
Chlorophyll have Mg+ in the center.
Chlorophyll pigments harvest energy (photons) by absorbing certain wavelengths (blue-420 nm and red-660 nm are most important).
Plants are green because the green wavelength is reflected, not absorbed.

17. Why leaves are green: interaction of light with chloroplasts

18. Location and Structure of Chlorophyll Molecules in Plants

19. Wavelength of Light (nm)
400
500
600
700
Short wave
Long wave
(more energy)
(less energy)

20. The Electromagnetic Spectrum

21. Absorption of Chlorophyll
violet blue green yellow orange red
Absorption
wavelength

22. Evidence that chloroplast pigments participate in photosynthesis: absorption and action spectra for photosynthesis in an alga

24. Question:
During the fall, what causes the leaves to change colors?

25. Fall Colors
In addition to the chlorophyll pigments, there are other pigments present.
During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments.
Carotenoids are pigments that are either red or yellow.

26. Redox Reaction
The transfer of one or more electrons from one reactant to another.
Two types:
1. Oxidation
2. Reduction

27. Oxidation Reaction The loss of electrons from a substance.
Or the gain of oxygen.
Oxidation
glucose
6CO H2O  C6H12O O2

28. Reduction Reaction The gain of electrons to a substance.
Or the loss of oxygen.
Reduction
glucose
6CO H2O  C6H12O O2

29. Oxidation (releases energy)
Combining with Oxygen
Loss of Electrons
Loss of Hydrogen
Reduction (absorbs energy)
Separation from Oxygen
Gain of Electrons
Gain of Hydrogen

30. Remember:
“Leo says Ger”
Loss of electrons is oxidation;
Gain of electrons is reduction. or
“Oil Rig”
Oxidation is loss; Reduction is
gain.

31. Breakdown of Photosynthesis
Two main parts (reactions).
1. Light Reaction or
Light Dependent Reaction
Produces energy from solar power (photons) in the form of ATP and NADPH.

32. Breakdown of Photosynthesis
2. Calvin Cycle or
Light Independent Reaction or
Carbon Fixation or
C3 Fixation
Uses energy (ATP and NADPH) from light rxn to make sugar (glucose).

33. An Overview of Photosynthesis: Cooperation of the Light Reactions and the Calvin Cycle

34. 1. Light Reaction (Electron Flow)
Occurs in the thylakoid membranes
During the light reaction, there are two possible routes for electron flow.
A. Cyclic Electron Flow
B. Noncyclic Electron Flow

35. A. Cyclic Electron Flow Occurs in the thylakoid membrane.
Uses Photosystem I only
P700 reaction center- chlorophyll a
Uses Electron Transport Chain (ETC)
Generates ATP only
ADP ATP P

36. How a Photosystem Harvests Light

37. A. Cyclic Electron Flow SUN ATP e- produced by ETC Photons
Primary
Electron
Acceptor e-
ATP
produced
by ETC
Photosystem I
Accessory
Pigments
SUN
Photons

38. Cyclic Electron Flow

39. B. Noncyclic Electron Flow
Occurs in the thylakoid membrane
Uses PS II and PS I
P680 rxn center (PSII) - chlorophyll a
P700 rxn center (PS I) - chlorophyll a
Uses Electron Transport Chain (ETC)
Generates O2, ATP and NADPH

40. Electron transport chain
Figure 10.13
Photosystem II
(PS II)
Photosystem-I
(PS I)
ATP
NADPH
NADP+
ADP
CALVIN
CYCLE
CO2
H2O O2
[CH2O] (sugar)
LIGHT
REACTIONS
Light
Primary
acceptor Pq
Cytochrome
complex PC e
P680 e– +
2 H+ Fd
reductase
Electron
Transport
chain
Electron transport chain
P700
+ 2 H+
+ H+
Produces NADPH, ATP, and oxygen 7 4 2 8 3 5 1 6

41. B. Noncyclic Electron Flow
P700
Photosystem I
P680
Photosystem II
Primary
Electron
Acceptor
ETC
Enzyme
Reaction
H2O
1/2O2 + 2H+
ATP
NADPH
Photon
2e-
SUN

42. B. Noncyclic Electron Flow
ADP +  ATP
NADP+ + H  NADPH
Oxygen comes from the splitting of H2O, not CO2
H2O  /2 O2 + 2H+ P
(Reduced)
(Reduced)
(Oxidized)

43. How Noncyclic Electron Flow During the Light Reactions Generates ATP and NADPH

44. Chemiosmosis Powers ATP synthesis. Located in the thylakoid membranes.
Uses ETC and ATP synthase (enzyme) to make ATP.
Photophosphorylation: addition of phosphate to ADP to make ATP.

45. Chloroplast
Stroma
Outer Membrane
Thylakoid
Granum
Inner Membrane

47. Chemiosmosis ADP + P ATP PS II PS I E T C Thylakoid Space
H+ H+
ATP Synthase
high H+
concentration H+
ADP + P
ATP
PS II
PS I E T C
low H+
Thylakoid
Space
SUN
(Proton Pumping)

48. The light reactions and chemiosmosis: the organization of the thylakoid membrane

49. Comparison of chemiosmosis in mitochondria and chloroplasts

50. Calvin Cycle Carbon Fixation (light independent rxn).
C3 plants (80% of plants on earth).
Occurs in the stroma.
Uses ATP and NADPH from light rxn and also uses CO2 from air.
To produce glucose: it takes 6 turns and uses 18 ATP and 12 NADPH.

51. The Calvin Cycle

52. Calvin Cycle (C3 fixation)
6CO2
6C-C-C-C-C-C
6C-C-C
6C-C-C-C-C
12PGA
RuBP
12G3P
(unstable)
6NADPH
6ATP
C-C-C-C-C-C
Glucose
(6C)
(36C)
(30C) C3
glucose

53. Calvin Cycle
Remember: C3 = Calvin Cycle C3
Glucose

54. A Review of Photosynthesis

55. Photorespiration Occurs on hot, dry, bright days. Stomates close.
Fixation of O2 instead of CO2.
Produces 2-C molecules instead of 3-C sugar molecules.
Produces no sugar molecules or no ATP.

56. Photorespiration
Because of photorespiration: Plants have special adaptations to limit the effect of photorespiration.
1. C4 plants
2. CAM plants

57. C4 Plants Hot, moist environments.
15% of plants (grasses, corn, sugarcane).
Divides photosynthesis spatially.
Light rxn - mesophyll cells.
Calvin cycle - bundle sheath cells.

58. C4 Plants Mesophyll Cell Bundle Sheath Cell C3 CO2 C-C-C PEP C-C-C-C
Malate
ATP
Bundle Sheath Cell
C-C-C
Pyruvic Acid
C-C-C-C
CO2 C3
Malate
Transported
glucose
Vascular
Tissue

59. C4 leaf anatomy and the C4 pathway

61. CAM Plants Hot, dry environments.
5% of plants (cactus and ice plants).
Stomates closed during day.
Stomates open during the night.
Light rxn - occurs during the day.
Calvin Cycle - occurs when CO2 is present.

63. CAM Plants Night (Stomata Open) Day (Stomata Closed) Vacuole C-C-C-C
Malate
CO2 C3
C-C-C
Pyruvic acid
ATP
PEP
glucose

64. C4 and CAM Photosynthesis Compared

65. Question:
Why would CAM plants close their stomata during the day?

66. List the reactants necessary for
photosynthesis to take place.
In terms of light absorption and
reflection explain why most
plants appear to be green.
Explain the role of carotenoids in
plants.