PowerLecture: Chapter 7

1. PowerLecture:Chapter 7 Where It Starts - Photosynthesis

2. Section 7.0: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change) • Section 7.0 : ASU Center for the Study of Early Events in Photosynthesis • Section 7.0 : When Did Photosynthesis Emerge on Earth? David Des Marais, Science, Sept. 8, 2000.

3. How Would You Vote? The following is the question for this chapter. See the "Polls and ArtJoinIn" for this chapter if your campus uses a Personal Response System,or have your students vote online. See national results below. • Should public funds be used to find potentially life supporting planets too far away for us to visit?

4. Impacts, Issues: Sunlight and Survival • Plants are autotrophs, or self-nourishing organisms • The first autotrophs filled Earth’s atmosphere with oxygen, creating an ozone (O3) layer • The ozone layer became a shield against deadly UV rays from the sun, allowing life to move out of the ocean

5. Sunlight and Survival Fig. 7-1, p.106

6. Sunlight and Survival p.107

7. Section 7.1: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change) • Section 7.1: Chemistry of Autumn Colors • Section 7.1: Molecule of the Month—Chlorophyll • Section 7.1: Foliage Afire: Why Leaves Change Colors. Esther McGuire. New York State Conservationist, Oct. 1998. • Section 7.1: Photochemistry of Chlorophyll. Bulletin of the South Carolina Academy of Science, 2002.

8. Electromagnetic Spectrum Shortest Gamma rays wavelength X-rays UV radiation Visible light Infrared radiation Microwaves Longest Radio waves wavelength

9. Photons • Packets of light energy • Each type of photon has fixed amount of energy • Photons having most energy travel as shortest wavelength (blue-violet light)

10. Visible Light • Wavelengths humans perceive as different colors • Violet (380 nm) to red (750 nm) • Longer wavelengths, lower energy Figure 7-2Page 108

11. Visible Light shortest wavelengths (most energetic) longest wavelengths (lowest energy) range of most radiation reaching Earth’s surface range of heat escaping from Earth’s surface gamma rays x rays ultraviolet radiation near-infrared radiation infrared radiation radio waves microwaves VISIBLE LIGHT 400 450 500 550 600 650 700 Wavelengths of light (nanometers) Fig. 7-2, p.108

12. Visible Light Wavelengths of light

13. Pigments • Color you see is the wavelengths not absorbed • Light-catching part of molecule often has alternating single and double bonds • These bonds contain electrons that are capable of being moved to higher energy levels by absorbing light

14. Variety of Pigments Chlorophylls a and b Carotenoids Anthocyanins Phycobilins

15. Chlorophylls Main pigments in most photoautotrophs chlorophyll a Wavelength absorption (%) chlorophyll b Wavelength (nanometers)

16. Accessory Pigments Carotenoids, Phycobilins, Anthocyanins beta-carotene phycoerythrin (a phycobilin) percent of wavelengths absorbed wavelengths (nanometers)

17. Pigments Fig. 7-3a, p.109

18. Pigments Fig. 7-3b, p.109

19. Pigments Fig. 7-3c, p.109

20. Pigments Fig. 7-3d, p.109

21. Pigments Fig. 7-3e, p.109

22. Pigments in Photosynthesis • Bacteria • Pigments in plasma membranes • Plants • Pigments and proteins organized into photosystems that are embedded in thylakoid membrane system

23. Section 7.2: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change) • Section 7.2: Milestones in Photosynthesis Research • Section 7.2: Photosynthetic Pigments in Bacteria and Plants • Section 7.2: Sunlight at Southall Green. Norman & Elaine Beale. Perspectives in Biology and Medicine, Summer 2001. • Section 7.2: Photosynthesis and Respiration in a Jar. Joseph Buttner. Science Activities, Summer 2000.

24. T.E. Englemann’s Experiment Background • Certain bacterial cells will move toward places where oxygen concentration is high • Photosynthesis produces oxygen

25. T.E. Englemann’s Experiment

26. T.E. Englemann’s Experiment Fig. 7-4a, p.110

27. T.E. Englemann’s Experiment Fig. 7-4c, p.110

28. T.E. Englemann’s Experiment Fig. 7-5, p.110

29. T.E. Englemann’s Experiment Englemann’s Experiment

30. Photosynthesis Energy-storing pathway Releases oxygen Requires carbon dioxide Aerobic Respiration Energy-releasing pathway Requires oxygen Releases carbon dioxide Linked Processes

31. Section 7.3: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change) • Section 7.3: MIT Biology Hypertextbook—Physics of Photosynthesis

32. Chloroplast Structure two outer membranes stroma inner membrane system (thylakoids connected by channels) Fig. 7-6, p.111

33. Photosynthesis Equation LIGHT ENERGY 12H2O + 6CO2 6O2 + C2H12O6 + 6H2O Water Carbon Dioxide Oxygen Glucose Water In-text figurePage 111

34. Photosynthesis Fig. 7-6a, p.111

35. Photosynthesis leaf’s upper epidermis photosynthetic cells (see next slide) vein stoma (gap) across lower leaf epidermis Fig. 7-6a, p.111

36. Photosynthesis two outer membranes thylakoid compartment thylakoid membrane system inside stroma stroma Fig. 7-6b, p.111

37. Photosynthesis SUNLIGHT O2 H2O CO2 NADPH, ATP light-dependant reactions light-independant reactions NADP+, ADP sugars CHLOROPLAST Fig. 7-6c, p.111

38. Photosynthesis Equation Sites of Photosynthesis

39. Reactants 12H2O 6CO2 Products 6O2 C6H12O6 6H2O Where Atoms End Up

40. Two Stages of Photosynthesis sunlight water uptake carbon dioxide uptake ATP ADP + Pi LIGHT-DEPENDENT REACTIONS LIGHT-INDEPENDENT REACTIONS NADPH NADP+ glucose P oxygen release new water

41. Arrangement of Photosystems water-splitting complex thylakoid compartment H2O 2H + 1/2O2 P680 P700 acceptor acceptor pool of electron carriers PHOTOSYSTEM II stroma PHOTOSYSTEM I

42. Section 7.4: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change) • Section 7.4: Photosynthetic Antennas and Reaction Centers • Section 7.4: The Amazing All-Natural Light Machine (light-harvesting molecule LH2). Mark Caldwell. scover, Dec. 1995.

43. Light-Dependent Reactions • Pigments absorb light energy, give up e-, which enter electron transfer chains • Water molecules split, ATP and NADH form, and oxygen is released • Pigments that gave up electrons get replacements

44. Light-Dependent Reactions photon Photosystem Light-Harvesting Complex Fig. 7-7, p.112

45. Light-Dependent Reactions Noncyclic pathway of electron flow

46. LIGHT- HARVESTING COMPLEX sunlight PHOTOSYSTEM II PHOTOSYSTEM I H+ NADPH e- e- e- e- e- e- NADP + + H+ e- thylakoid compartment H2O H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ O2 H+ thylakoid membrane stroma ATP ADP + Pi cross-section through a disk-shaped fold in the thylakoid membrane H+ Fig. 7-8, p.113

47. Section 7.5: Weblinks and InfoTrac See the latest Weblinks and InfoTrac articles for this chapter online or click highlighted articles below (articles subject to change)

48. Photosystem Function: Harvester Pigments • Most pigments in photosystem are harvester pigments • When excited by light energy, these pigments transfer energy to adjacent pigment molecules • Each transfer involves energy loss

49. Pigments in a Photosystem reaction center

50. Photosystem Function: Reaction Center • Energy is reduced to level that can be captured by molecule of chlorophyll a • This molecule (P700 or P680) is the reaction center of a photosystem • Reaction center accepts energy and donates electron to acceptor molecule