1. The Working Cell: Energy from Sunlight
Chapter 8 Notes

2. Ch. 8 The Working Cell: Energy from Light
8.1 Photosynthesis uses light energy to make food.
8.2 The light reactions convert light energy to chemical energy.
8.3 The Calvin cycle makes sugar from carbon dioxide.
8.4 Photosynthesis has a global impact.

3. 8.1 Photosynthesis uses light energy to make food.
Objectives
Describe the structure of a chloroplast.
Identify the overall reactants and products of photosynthesis.

4. 8.1 Photosynthesis uses light energy to make food.
Key Terms
Chloroplast
Chlorophyll
Stroma
Thylakoid
Light reactions
Calvin cycle

5. 8.1 Photosynthesis uses light energy to make food.
Photosynthesis is the process by which plants & other producers convert energy of sunlight to energy stored in organic molecules.
Chloroplast – organelle where photosynthesis takes place
Chlorophyll – chemical that gives a green color to chloroplasts.

6. 8.1 Photosynthesis uses light energy to make food.
Chloroplasts structure is key to its function
Has an inner & outer membrane
Inner membrane encloses a thick fluid called the stroma
Suspended in the stroma are thylakoids – disk-shaped sacs

7. 8.1 Photosynthesis uses light energy to make food.
Cellular respiration – fall of electrons form glucose to oxygen gives off energy, which is then used to make ATP.
Photosynthesis is the opposite – electrons from water are boosted uphill by the energy from sunlight.

8. 8.1 Photosynthesis uses light energy to make food.
Excited electrons along with carbon dioxide & water are used by chloroplasts to produce glucose & oxygen.
                                                                                                                               

9. 8.1 Photosynthesis uses light energy to make food.
Photosynthesis occurs in 2 main stages.
Light reactions – convert sunlight to chemical energy
Stored in NADPH & ATP
Calvin cycle – makes sugar from carbon dioxide and H+ ions from the splitting of water.

10. 8.1 Concept check (QUIZ)
Draw & label a simple diagram of a chloroplast that includes the following structures: outer & inner membranes, stroma, thylakoids.
What are the reactants of photosynthesis, what are the products?
Name the 2 main stages of photosynthesis. How are they related?

11. 8.2 The light reactions convert light energy to chemical energy
Objectives
Explain how light interacts with pigments.
Describe how photosystems help harvest light energy.
Identify the chemical products of the light reactions.

12. 8.2 The light reactions convert light energy to chemical energy
Key Terms
Wavelength
Electromagnetic spectrum
Pigment
Paper chromatography
photosystem

13. 8.2 The light reactions convert light energy to chemical energy
Light energy is a form of electromagnetic energy
Travels in waves (similar to ocean waves)
Measured by wavelength – distance between 2 adjacent waves.

14. 8.2 The light reactions convert light energy to chemical energy
Different forms of electromagnetic energy have characteristic wavelengths
Electromagnetic spectrum – the range of types of electromagnetic energy

15. 8.2 The light reactions convert light energy to chemical energy
Pigments – chemical compounds that give a substance its color.
Cause different wavelengths to be…
Absorbed
Transmitted
Reflected

16. 8.2 The light reactions convert light energy to chemical energy
Paper chromatography – lab technique used to observe different pigments in substances.

17. 8.2 The light reactions convert light energy to chemical energy
Harvesting light energy
Photosystems – clusters of pigment molecules
Chlorophyll a
Chlorophyll b
Carotenoids

18. 8.2 The light reactions convert light energy to chemical energy
Harvesting light energy
1)Pigments absorb light energy
2)transfer energy to electrons
3)transfer energy to electronacceptor.
4)converts to ATP or NADPH.

19. 8.2 The light reactions convert light energy to chemical energy
Chemical products of the light reactions
Oxygen, released as a waste product of the 1st photosystem.
ATP – produced by the release of energy by the electron transport chain between photosystems.
NADPH – produced by the second photosystem

20. 8.2 Concept check Explain why a leaf appears green.
Describe what happens when a molecule of chlorophyll a absorbs light.
Besides oxygen, what 2 molecules are produced by the light reactions?
Where in the chloroplast do the light reactions take place?

21. 8.3 The Calvin cycle makes sugar from carbon dioxide
Objectives
Explain how the Calvin cycle makes sugar.
Summarize the overall process of photosynthesis.

22. 8.3 The Calvin cycle makes sugar from carbon dioxide
Called a cycle because the starting material RuBP is regenerated each time the process occurs
RuBP is a 5 carbon sugar

23. 8.3 The Calvin cycle makes sugar from carbon dioxide
Into the Calvin cycle
Carbon dioxide
ATP
NADPH
From air
From light reactions

24. 8.3 The Calvin cycle makes sugar from carbon dioxide
Outputs of Calvin cycle
G3P (an energy rich sugar)
Not yet glucose
Used by plant to make glucose
ADP + P
NADP+

25. 8.3 The Calvin cycle makes sugar from carbon dioxide
Summary of photosynthesis
Light reactions
Convert light energy to chemical energy
Occurs in thylakoids
Uses water (reactant) & releases oxygen (product)

26. 8.3 The Calvin cycle makes sugar from carbon dioxide
Occurs in stroma
Uses ATP & NADPH
Converts carbon dioxide (reactant) to sugar (product)

27. 8.3 Concept check What are the inputs & outputs of the Calvin cycle?
Which stage of photosynthesis uses each reactant from the overall photosynthesis equation? Which stage generates each product from the overall photosynthesis equation?

28. 8.3 Concept check Why is the Calvin cycle called a cycle?
What molecule is the direct product of photosynthesis? How is that molecule then used by the plant cell?

29. 8.4 Photosynthesis has a global impact.
Objectives
Describe the path of carbon in the carbon cycle.
Explain how photosynthesis is related to climate.

30. 8.4 Photosynthesis has a global impact.
Key Terms
Carbon cycle
Greenhouse effect

31. 8.4 Photosynthesis has a global impact.
Processes that occur on a global scale depend on chloroplasts & mitochondrion
Carbon cycle – process by which carbon moves from inorganic to organic & back to inorganic.

32. 8.4 Photosynthesis has a global impact.
Path of carbon in the carbon cycle
Producers convert inorganic carbon to organic carbon through photosynthesis.
Consumers eat the producers, may be eaten by other consumers.
Cellular respiration by both producers & consumers eventually carbon dioxide to the atmosphere

33. 8.4 Photosynthesis has a global impact.
Plants & other photosynthetic organisms make about 160 billion metric tons of organic material.
80 trillion copies of book
25 stacks reaching to the sun.

34. 8.4 Photosynthesis has a global impact.
Carbon dioxide in the atmosphere traps in heat – greenhouse effect
Keeps world climate warm enough for living things.
Average 10°C warmer than it would be.
Amount of carbon dioxide in atmosphere is rising.

35. Photosynthesis
                                                                                                                                                                           

36. Stages of Photosynthesis
                                                                                                                               

37. Electromagnetic spectrum
                                                                                                                         

38. Pigments & Color
                                                                                              

39. Harvesting Light Energy
                                                                                                                                                                           

40. Chemical products of light reactions

41. Calvin cycle

42. Photosynthesis
                                                                                                                                  

43. Greenhouse effect
                                                                                                                               

44. Light Waves