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Photosynthesis: The Light Reactions Part 1 of 4


Delivered on: 9 OCTOBER 2023


This video provides a captivating introduction to the wonders of photosynthesis, exploring the fundamental role of light, pigments, and chlorophyll in capturing and converting solar energy. 🌿 We'll delve into the general concepts that underpin this essential biological process.


What you'll learn:

  • Photosynthesis in Green Plants:  Understand the basic principles of photosynthesis, including the light-dependent reactions that occur within chloroplasts and the carbon fixation reactions that produce sugars.

  • The Nature of Light:  We'll explore the dual nature of light as both a particle and a wave, and how photons carry energy that plants can harness.

  • Chlorophyll and Light Absorption:  Discover the fascinating properties of chlorophyll, the primary pigment responsible for absorbing light energy, and how its excited state drives photosynthesis.

  • Photosynthetic Pigments:  Learn about the diversity of pigments found in photosynthetic organisms, each with unique light-absorbing properties, and their roles in capturing a wider range of the light spectrum.


9.1 Photosynthesis in Green Plants

Within chloroplasts, chlorophylls absorb light energy for the oxidation of water, releasing oxygen and generating NADPH and ATP (thylakoid reactions).


NADPH and ATP are used to reduce carbon dioxide to form sugars (carbon fixation reactions, treated in Chapter 10).


9.2 General Concepts

Light behaves as both a particle and a wave, delivering energy as photons, some of which are absorbed and used by plants (Figures 9.1,9.2,9.3).


Light-energized chlorophyll may fluoresce or transfer energy to another molecule to drive chemical reactions (Figures 9.4, 9.10).


All photosynthetic organisms contain a mixture of pigments with distinct structures and light-absorbing properties (Figures 9.6, 9.7).


LIST OF KEY TERMS

1. absorption spectrum

2. accessory pigments

3. action spectrum

4. antenna complex

5. ATPase

6. ATP synthase

7. bacteriochlorophylls

8. bleached

9. carbon fixation reactions

10. carotenoids

11. CF0–CF1

12. charge-separated state

13. chemical potential

14. chlorophyll a/b antenna proteins

15. chlorophylls

16. cyclic electron flow

17. cytochrome b6f complex

18. cytochrome f

19. endosymbiosis

20. energy conversion efficiency

21. energy transfer

22. envelope

23. ferredoxin (Fd)

24. ferredoxin–NADP+ reductase (FNR)

25. FeSA

26. FeSB

27. Fe–S centers

28. FeSX

29. fluorescence

30. fluorescence resonance energy transfer

31. frequency

32. grana lamellae

33. integral membrane proteins

34. light energy

35. light-harvesting complex II (LHCII)

36. lowest excited state

37. non-Mendelian, or maternal, inheritance

38. Nonphotochemical quenching

39. oxygen-evolving complex (OEC)

40. P680

41. P700

42. P870

43. Pheophytin

44. photochemistry

45. Photoinhibition

46. photons

47. photophosphorylation

48. photoprotection

49. photosystems I and II (PSI and PSII)

50. plastocyanin (PC)

51. plastohydroquinone (PQH2)

52. proton motive force

53. Q cycle

54. quanta

55. quantum yield

56. quenched

57. reaction center complex

58. reactive oxygen species

59. Rieske iron–sulfur protein

60. singlet oxygen

61. stroma

62. stroma lamellae

63. thylakoid reactions

64. thylakoids

65. transit peptide

66. uncoupled

67. wavelength

68. xanthophylls


Video Timestamps:

0:00 Introduction

4:04 Introduction about the syllabus of the course

5:51 Introduction on the lesson of the semester and reference book

7:44 Quick test

12.32 General Concept: Properties of light in photosynthesis

16.43 Properties of light

17.35 Wavelength and energy

19.02 Wavelength and light colour

21.09 Concept of light as electromagnetic radiation

23.45 How light is created

27:20 Visible light spectrum

33:12 Duality nature of light, wave-particle duality

37:50 Absorption of photosynthetically active light changes the electronic states of chlorophyll

40:50 Properties of chlorophyll

46:39 Absorption spectrum

49:20 Chlorophyll excited state

51:00 Destiny excited chlorophyll

51:51 Photosynthetic pigment absorbs the light that powers photosynthesis

1:02:48 Spectrum of absorption chlorophyll pigment

1:06:10 Accessory pigments

1:07:20 Distribution of chlorophyll and other photosynthetic pigments

1:11:14 Key experiments in understanding photosynthesis

1:11:50 Schedule for the classes and practical


Location:

Faculty of Agriculture, Universiti Putra Malaysia

Fakulti Pertanian, Universiti Putra Malaysia, 43000 Seri Kembangan, Selangor

XPMM+9J Seri Kembangan, Selangor

2.9845517506267742, 101.73803356324866


Attribution 4.0 International — CC BY 4.0 - Creative Commons

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