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Photosynthesis

Photosynthesis

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Photosynthesis

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  1. Photosynthesis

  2. Introduction • Autotrophs: • Photoautotrophs : • Chemoautotrophs

  3. Important structures • Chloroplast • Thylakoids: • Grana: • Stroma:

  4. Chloroplast two outer membranes thylakoid membrane system Organelle of photosynthesis in plants and algae stroma thylakoid compartment

  5. a A look inside the leaf b One of the photosynthetic cells inside leaf leaf’s upper epidermis photosynthetic cell in leaf leaf vein Leaf Structure leaf’s lower epidermis

  6. Properties of Light • White light from the sun is composed of a range of wavelengths. • All colors

  7. Chlorophyll • Chlorophyll is the main pigment that absorbs sunlight. • Chlorophyll absorbs blue light and to a lesser extent, red light. • It reflects green light

  8. What do chlorophyll and fireworks have in common?

  9. Photosynthesis: Light-Dependent • Photosystems - chlorophyll a molecule....

  10. What does Chlorophyll absorb?

  11. Photosynthesis: Light-Dependent • pigment absorbs light energy

  12. Two Potential Fates of Excited Electrons Electron returns to resting, unexcited state. Excited electrons are passed to other atoms.

  13. Photosynthesis: Light-Dependent • electrons in the pigments become excited • energy (but not the electrons) is transferred • excites the electrons in a chlorophyll a molecule at the center of the photosystem.

  14. Photosynthesis: Light-Dependent

  15. The Passing of Electrons in Their Excited State Molecules that gain electrons always carry greater energy than before receiving them

  16. Photosynthesis: Light-Dependent • chlorophyll that is the reaction center • Splits water

  17. Photosynthesis: Light-Dependent

  18. Photosynthesis: Light-Dependent • chlorophyll a continually loses its excited electrons to a nearby molecule, • replacement electrons come from water.

  19. Photosynthesis: Light-Dependent

  20. Photosynthesis: Light-Dependent • Protons rush out of the thylakoid sacs with great force—to build energy-storing ATP molecules

  21. Light-Dependent

  22. Photosynthesis: Light-Dependent • Product #1 of the “Photo” Portion of Photosynthesis: ATP • Product #2: NADPH • Product #3 (waste): O2

  23. Photosynthesis Equation LIGHT ENERGY 6H2O + 6CO2 6O2 + C6H12O6 6 water + 6 carbon dioxide 6 oxygen + glucose

  24. Suppose a large meteor hit the earth. How could smoke and soot in the atmosphere wipe out life far beyond the area of direct impact?

  25. Photosynthesis • Two stages:

  26. Light-dependent Reactions • require light to work

  27. smoke and soot

  28. smoke and soot

  29. smoke and soot

  30. Light-independent Reactions • do not require light

  31. Two Steps in Photosynthesis sunlight H2O O2 CO2 Where the two stages of photosynthesis occur inside the chloroplast NADPH, ATP light-dependent reactions light-independent reactions NADP+, ADP sugars

  32. Photosynthesis: Light-inDependent • Calvin Cycle • whether or not light is present. • Occur in the stroma

  33. Light-inDependent • take the energy from ATP + energized ions from NADPH + carbon dioxide to make glucose or sugar. • carbon dioxide into CH2O.

  34. Photosynthesis: Light-inDependent

  35. Summary of Photosynthesis sunlight Light Dependent Reactions 6O2 12H2O ATP ADP + Pi NADP+ NADPH 6CO2 Calvin- Benson cycle Light Independent Reactions 6 RuBP 12 PGAL 6H2O phosphorylated glucose P end products (e.g., sucrose, starch, cellulose)

  36. Photosynthesis: Light-inDependent

  37. C3 Plants

  38. C4 Plants