1. PHOTOSYNTHESIS

2. Student directions: Watch the introductory video(s)
Continue with the ppt
Answer questions on your own paper. These will be your notes. BE DETAILED!
Slides following the questions will help you
Also use your book and other internet resources to add details.

3. Introductions Vidios to watch:

4. Background- What is the definition of photosynthesis?
Write a summary chemical reaction for photosynthesis. Make sure it is a balanced reaction (same number of each kind of element on both sides of the arrow).
What are the products of this reaction?
What are the reactants of this reaction?

5. Photosynthesis Anabolic (small molecules combined)
Endergonic (stores energy)
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

6. Leaf Structure Draw a crossecton diagram of a leaf. Include and label:
The main kind of cells in leaves that do the majority of the photosynthesis.
Incoming light (photons)
H2O entering and Glucose (sugar) leaving.
Location and directions of flow of O2 and CO2

7. Click here to link to a great website summarizing leaf and Chloroplast structure.

8. Plants Autotrophs – produce their own food (glucose)
Process called photosynthesis
Mainly occurs in the leaves:
a. stoma - pores
b. mesophyll cells
Mesophyll
Cell
Chloroplast
Stoma

9. Stomata (stoma)
Pores in a plant’s cuticle through which water vapor and gases (CO2 & O2) are exchanged between the plant and the atmosphere.
Guard Cell
Oxygen
(O2)
Stoma
Carbon Dioxide
(CO2)
Found on the underside of leaves

10. Chloroplast structure
Diagram a Chloroplast. Include and label:
Granum
Thylakoid
Stroma
Electron transport chain
Click here to link to a great website summarizing leaf and Chloroplast structure.

11. Mesophyll Cell of Leaf Photosynthesis occurs in these cells! Nucleus
Cell Wall
Chloroplast
Central Vacuole
Photosynthesis occurs in these cells!

12. Chloroplast Organelle where photosynthesis takes place.
Stroma
Outer Membrane
Thylakoid
Granum
Inner Membrane
Thylakoid stacks are connected together

13. Grana make up the inner membrane
Thylakoid
Thylakoid Membrane
Granum
Thylakoid Space
Grana make up the inner membrane

14. Chlorophyll What molecule actually captures the photons from light?
What element is in the center of this molecule that must be available in the soil?
What wavelength ranges of light does chlorophyll absorb best?
Why do leaves appear green?

16. Absorption of Light by Chlorophyll
Chlorophyll absorbs blue-violet & red light best
violet blue green yellow orange red
Absorption
wavelength

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

18. 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.

19. Energy transfers
What is the most basic molecule for energy transfer in all cells?
How do plants store the energy in photons in ATP?

20. Energy for Life on Earth
Sunlight is the ULTIMATE energy for all life on Earth
Plants store energy in the chemical bonds of sugars
Chemical energy is released as ATP during cellular respiration

21. Structure of ATP ATP stands for adenosine triphosphate
It is composed of the nitrogen base ADENINE, the pentose (5C) sugar RIBOSE, and three PHOSPHATE groups
The LAST phosphate group is bonded with a HIGH ENERGY chemical bond
This bond can be BROKEN to release ENERGY for CELLS to use

22. Removing a Phosphate from ATP
Breaking the LAST PHOSPHATE bond from ATP, will ---
Release ENERGY for cells to use
Form ADP
Produce a FREE PHOSPHATE GROUP

23. High Energy Phosphate Bond

24. FREE PHOSPHATE can be re-attached to ADP reforming ATP
Process called Phosphorylation

25. Phosphorylation

26. Parts of Photosynthesis

27. Two Parts of Photosynthesis
Two reactions make up photosynthesis:
1.Light Reaction or Light Dependent Reaction -
Produces energy from solar power (photons) in the form of ATP and NADPH.
SUN

28. Two Parts of Photosynthesis
2. Calvin Cycle or Light Independent Reaction
Also called Carbon Fixation or C3 Fixation
Uses energy (ATP and NADPH) from light reaction to make sugar (glucose).

29. 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

30. 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

31. Cyclic Electron Flow
P700
Primary
Electron
Acceptor e-
ATP
produced
by ETC
Photosystem I
Accessory
Pigments
SUN
Photons
Pigments absorb light energy & excite e- of Chlorophyll a to produce ATP

32. Light-dependent Reactions
Photosystem: light capturing unit, contains chlorophyll, the light capturing pigment
Electron transport system: sequence of electron carrier molecules that shuttle electrons, energy released to make ATP
Electrons in chlorophyll must be replaced so that cycle may continue-these electrons come from water molecules, Oxygen is liberated from the light reactions
Light reactions yield ATP and NADPH used to fuel the reactions of the Calvin cycle (light independent or dark reactions)

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

36. Noncyclic Electron Flow
P700
Photosystem I
P680
Photosystem II
Primary
Electron
Acceptor
ETC
Enzyme
Reaction
H2O
1/2O2 + 2H+
ATP
NADPH
Photon
2e-
SUN
H2O is split in PSII & ATP is made, while the energy carrier NADPH is made in PSI

37. Noncyclic Electron FlowP
ADP +  ATP
NADP+ + H  NADPH
Oxygen comes from the splitting of H2O, not CO2
H2O  /2 O2 + 2H+

38. Chemiosmosis Powers ATP synthesis
Takes place across the thylakoid membrane
Uses ETC and ATP synthase (enzyme)
H+ move down their concentration gradient through channels of ATP synthase forming ATP from ADP

39. 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)

40. Calvin Cycle (light independent or “dark” reactions)
ATP and NADPH generated in light reactions used to fuel the reactions which take CO2 and break it apart, then reassemble the carbons into glucose.
Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO2) and making an organic molecule out of it (glucose)
Simplified version of how carbon and energy enter the food chain

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

43. Energy Storage
11. How do plants store the energy in ATP into Glucose?

44. Chloroplast STROMA– where Calvin Cycle occurs Outer Membrane Thylakoid
Granum
Inner Membrane

45. 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

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

47. STOP HERE
for now

48. 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

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

50. C4 Plants Hot, moist environments
15% of plants (grasses, corn, sugarcane)
Photosynthesis occurs in 2 places
Light reaction - mesophyll cells
Calvin cycle - bundle sheath cells

51. C4 Plants Mesophyll Cell Bundle Sheath Cell C3 CO2 C-C-C PEP C-C-C-C
Malate-4C sugar
ATP
Bundle Sheath Cell
C-C-C
Pyruvic Acid
C-C-C-C
CO2 C3
Malate
Transported
glucose
Vascular
Tissue

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

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

54. Why do CAM plants close their stomata during the day?
Question:
Why do CAM plants close their stomata during the day?

55. Cam plants close their stomata in the hottest part of the day to conserve water

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

58. 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, orange, or yellow

59. Redox Reaction
The transfer of one or more electrons from one reactant to another
Two types:
1. Oxidation is the loss of e-
2. Reduction is the gain of e-

60. Oxidation Reaction
The loss of electrons from a substance or the gain of oxygen.
Oxidation
glucose
6CO H2O  C6H12O O2
Carbon dioxide
Oxygen
Water

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