1. Chapter 7: Photosynthesis: Acquiring Energy From the Sun

2. Define Photosynthesis
The conversion of solar energy into the chemical energy of a carbohydrate.
Photosynthetic organisms are called autotrophs.

3. An Overview of Photosynthesis
Notice the levels of organization in a typical leaf.
Starting at the cuticle of a leaf and gradually moving down in size to the thylakoid.
Eventually, we’ll look at the pigment molecules

4. Page 122_01

5. Page 124_01

7. Fig. 10.2b

9. The overall process of photosynthesis

10. How Plants Capture Energy From Sunlight
Recognize that pigments capture energy from sunlight: Chlorophyll a and carotenoids.
In what form does sunlight energy arrive at the plant?
As the mighty photon! (From the visible light spectrum)
Plants use light in the visible light spectrum.

11. Figure 7.1

12. Recognize the importance of the structure and function of chlorophyll (a pigment that reflects green)

13. Fig. 10.6

14. Recognize the other accessory pigments and their function.

15. Organizing Pigments into Photosystems
The light-dependent reactions (or simply the light reactions) occur on membranes.
Bacteria: the LDR occur within the plasma membrane
Algae: The LDR occur on membranes within the cell.
Plants: The LDR occur within the membranes of the thylakoid.
Photosystems are an important part of the LDR in plants

16. Figure 7.5

17. How a photosystem works

18. What happens in the light dependent reactions?
Thank you to the sun
And the rain.
Note that ATP and
NADPH are produced

19. Another diagram of the
Light Reactions.

21. Here is a closer look at making ATP in the light dependent reactions

22. Here we see basically the same thing as in the previous slide, but with the inclusion of the “magic door!” The magic door is officially called ATP synthase

23. Following is an overall view of the light dependent reactions.
It’s a little different view, but it should make sense to you (hopefully)
Following the next diagram are a series of pictures with descriptions, to help clarify what is going on.

25. 1
It’s redox reaction time!
And, these moving electrons (due to the redox reactions) generate the movement of hydrogen ions across the thylakoid membrane

26. 2
And, these moving hydrogen ions collect and build up a concentration gradient inside the thylakoid.
And, this concentration gradient creates kinetic energy, the energy of movement, of H+

27. 3
So, the H+ flow through the magic door! (ATP synthase)
The kinetic energy of H+ flowing through the ATP synthase door phosphorylates ADP into ATP

28. 4
And, then we have energy to build sugar!
Sunlight energy has been transformed into ATP.
It has also allowed NADP+ to be reduced to NADPH.
ATP energy and NADPH will now be used to help build sugar molecules by reduction and phosphorylation. (In the Calvin cycle, located in the stroma)

29. Light reactions animation

30. Building New Molecules [in the Calvin Cycle
The Calvin Cycle uses the materials provided by the light independent reactions:
1) Energy (ATP) to drive the endergonic reactions
2) Reducing power: NADPH to provide a source of hydrogens and the energetic electrons needed to bind them to carbon.

31. Figure 7.10

32. Figure 7.11
It’s Rrrrrubissco!

33. Remember these events of the Calvin Cycle..
1) The Fixation of Carbon Dioxide
2) Don’t forget the role of rubisco (ding!)
3) The Reduction of Carbon Dioxide (What is reduction?)
4) And, finally, the regeneration of RuBP

34. Calvin cycle animation

35. Fig

36. Ahhhh….. Done!
“Really?!”