Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It occurs in two stages: in the light-dependent reactions, sunlight is absorbed and used to convert carbon dioxide and water into glucose, producing oxygen as a byproduct. In the light-independent reactions, the glucose is then assembled from carbon dioxide using energy from the light reactions. The light reactions take place in chloroplasts within plant cells, while the dark reactions occur in the chloroplast stroma. Photosynthesis is essential for producing oxygen and food on Earth.

1. Photosynthesis

3. The Photosynthetic Equation 6CO 2 carbon dioxide + 6H 2 O water + light energy  sunlight C 6 H 12 O 6 glucose (sugar) + 6O 2 oxygen Photosynthesis occurs in plants, algae, and some prokaryotes Photosynthetic organisms are autotrophs (“self- feeders”) Photosynthesis in plants occurs within chloroplasts

5. Interconnections: Photosynthesis & Respiration

7. Structures of Photosynthesis

11. Leaf Structure Mesophyll Cells Upper Epidermis Lower Epidermis Vein Stoma

14. Chloroplast Structure Inner & Outer Membranes Thylakoids Granum Stroma (space)

16. Light, Chloroplast Pigments, & Photosynthesis Wavelength (nanometers, nm) Gamma Rays X-Rays UV Infrared Micro- waves Radio Waves Visible Light 400 450 500 550 600 650 700 750

20. Absorption Spectra Visible Light Chlorophyll Carotenoids Phycocyanin Collectively 0 20 40 60 80 100 % Light Absorption 400 450 500 550 600 650 700 750 Wavelength (nanometers) 400 450 500 550 600 650 700 750

21. Overview of Photosynthesis Glucose O 2 Light-Dependent Reactions (in thylakoids) Light-Independent Reactions (in stroma) Depleted Carriers (ADP, NADP + ) Energized Carriers (ATP, NADPH) H 2 O CO 2

22. The Photosystems

25. Thylakoid Structure & Light-Dependent Reactions

26. Oxygen as a By-product

27. Chemiosmosis 1

28. Chemiosmosis 2

34. The C 3 Cycle of Carbon Fixation …or… Dark Reactions …or… Light-Independent Reactions …or… Calvin Cycle …or… Calvin-Benson Cycle

37. A Summary of Photosynthesis Light-dependent reactions occur in thylakoids Light- independent reactions (c 3 cycle) occur in stroma

42. C 3 Plants & the Pathway C 3 plants use the C 3 pathway In a C 3 plant, most chloroplasts are in mesophyll cells.

43. C 3 Plants & the Pathway Much photorespiration occurs under hot, dry conditions

44. C 4 Plants & the C 4 Pathway C 4 plants use the C 4 pathway In a C 4 plant, both mesophyll & bundle-sheath cells contain chloroplasts.

45. C 4 Plants & the C 4 Pathway Almost no photorespiration occurs under hot, dry conditions. CO 2 is captured with a highly specific enzyme. Much glucose synthesis occurs. Mesophyll cell in a C 4 plant Bundle-sheath cell in a C 4 plant

46. The end