1. Photosynthesis

2. Plant Photosynthesis internal leaf structure chloroplasts
Figure: 06-01
Title:
An overview of photosynthetic structures.
Caption:
outer membrane
inner membrane
thylakoid

3. Well most of it anyway……
Photosynthesis
Where does the energy come from that sustains all life?
The Sun!!
Well most of it anyway……

4. Vocabulary
Photosynthesis – the process of capturing and transforming the energy of sunlight into chemical energy sugars
Autotrophs – capable of making food from simple inorganic substances (plants)
Heterotrophs – organism that cannot make their own food (animals)
Chlorophylls – Photosynthetic pigments
Chloroplast – are the organelles containing photosynthetic pigments
Thylakoids – Photosynthetic membranes found in the chloroplast
Grana – Stacks of Thylakoids
Stroma – Regions between the grana

5. Structures Involved in Photosynthesis

6. Chloroplast Terms Inner Membrane Outer Membrane Thylakoid Stroma
Granum

7. How Can Plants Do It?
Plants have pigments that allow them to absorb a certain wavelengths of light.
Chloroplasts hold chlorophyll, a pigment that absorbs light energy that can be turned into chemical energy.
All visible light that is not absorbed by the pigments is reflected
There is one color of light that plants do not absorb very well, green.

8. Photosystems use some wavelengths of light but reflect others…

9. What is photosynthesis?
The process of converting solar energy into chemical energy. (Chloroplast)
Plants only use water (H2O) and carbon dioxide (CO2) and light energy to create sugars (C6H12O6) = chemical energy. (Autotroph)
Heterotrophs then consume this sugar and break it apart to get the chemical energy (ATP from mitochondria) to carry out their life processes

10. Equation Photosynthesis
6CO H2O + hv C6H12O6 +6O2 +6H2O
hv designates sun light
you should memorize this equation!! you will see it again

11. Photosynthesis Reactants and Products
Light
Energy
Reactants:
6 CO2
12 H2O
Products:
C6H12O6
6 H2O
6 O2

12. Types of Photosynthetic Pigments
Types of Chlorophyll
Chlorophyll a absorbs red and purple wavelengths
Chlorophyll b absorbs blue wavelengths
Xanthophylls - absorb yellow light and transfer the energy to chlorophyll a
Carotenes - absorb orange light and transfer the energy to chlorophyll a
The combination of Chlorophyll and photosynthetic pigment membranes (thylakoids) are vital for converting light energy into chemical energy

13. Different pigments absorb light differently

14. Different pigments absorb light differently

15. The electromagnetic spectrum
PAR = photosynthetically available radiation

16. Fall Facts
The Carotenes and Xanthophylls can be seen in the fall when the Chlorophyll begins to break down

17. The 2 stages of photosynthesis
1. Light reactions
- Light reactions absorb and convert sunlight into ATP + NADPH
2. Dark reactions
- Dark reactions use ATP + NADPH + CO2 to form sugars (stored chemical energy)

18. Overview of Photosynthesis
Dark Reactions
CO2
ATP
NADPH
Light Reactions
Sugars
H2O O2

19. Photosynthetic pigments are arranged as “photosystems”

20. Light Dependent Reactions
1. Light energy is absorbed by the photosynthetic pigments this occurs on the thylakoid membrane that energy is used to break H2O apart.

21. Light Dependent Reactions Continued
2. H2O is broken apart into 2H+, O, and 2 free electrons These E- are trapped in the thylakiod membrane. The 2e- will be energized by the light energy absorbed and used in an electron transport chain to produce ATP. The 2H+ are transferred to NADP making NADPH and collect the 2 free electrons it lost ealier. This NADPH will be used to make sugars in the Calvin Cycle.
- The free O combines with another molecule of O to make O2 and it is released from the plant as a waste product
Products of the light reactions include ATP, NADPH (both will be used in the Calvin Cycles – Dark reactions) and free O2

22. A photosystem is a light gathering antenna complex with associated pigment molecules- a couple hundred chlrorophylls and accessory pigments
Two cooperating photosystems- discovered on this campus by Professor Robert Emerson.
Non-cyclic electron transport.
The reaction center- a special chlorophyll molecule is at its heart.

23. How plants harness energy from sunlight…
Photosynthetic pigments
Chlorophylls a – the “main” photosynthetic pigment
Accessory pigments..
Chlorophyll b
Carotenoids

24. Light Independent Reactions (Calvin Cycle)
Where the products from the light reactions (ATP, and NADPH) are used to fix CO2 into sugars!
Occurs in the stroma of the chloroplast.
The new sugars are then released into the cell to be used for energy or as building blocks

25. The products of Photosynthesis
Sugars – Used for energy by the mitochondria
Sugars – used to make cell walls
Molecular Oxygen – used to break down sugar to obtain energy (plant mitochondria)
Molecular Oxygen – if not used is released as a waste product

27. The Breakdown of Photosynthesis
includes
Light-
dependent
reactions
Calvin cycle
takes place in
uses
use
take place in
Thylakoid
membranes
Stroma
NADPH
ATP
Energy from
sunlight
to produce of
to produce
ATP
NADPH O2
Chloroplasts
High-energy
sugars

28. Feel The Light
Write a story about the process of photosynthesis from the perspective of a ray of sun or a plant cell.
Be sure to include
- Plants, Leaves, Cells, Chloroplast, Thyakoids, Grana, Stroma
- Chlorophylls, accessory pigments, what they absorb, and were they can be found
- Light and Dark reactions
- Reactants and products of photosynthesis
- Equation of photosynthesis