Photosynthesis

1. Chapter 3 Photosynthesis Where does all that glucose come from?

2. How does it do that?

3. CO2 CO2 CO2 CO2 CO2 CO2 radiant energy What is it? • Photosynthesis uses radiant energy from the sun to fix carbon dioxide into carbohydrates • The captured radiant energy is stored within the bonds of the carbohydrate as chemical energy Photosynthesis glucose

4. Photosynthesis is used by many autotrophs to make their own food • egs. vascular plants, algae, cyanobacteria

5. That’s a lot of photosynthesis

6. http://www.smhi.se/weather/baws_ext/info/2004/Baltic_algae_2004_en.htmhttp://www.smhi.se/weather/baws_ext/info/2004/Baltic_algae_2004_en.htm

7. H+ H+ O2 H2O Energy glucose CO2 Overall (Net) Equation Photosynthesis CO2 + H2O + energy  glucose + O2

8. H+ H+ O2 H2O Energy glucose CO2 Overall (Net) Equation Cellular Respiration Photosynthesis glucose + O2 CO2 + H2O + energy Photosynthesis and Cellular Respiration appear to be reverse processes, but they use very different mechanisms

9. Similarities • Both cellular respiration and Photosynthesis are similar in that both use: • electron transport chains • dissolved enzymes • membrane-enclosed space for chemiosmosis

10. Plant Tissues • Plants are made of various types of tissues • egs. Stem, leaves, roots, reproductive organs • The main site of photosynthesis is the leaves, although chloroplasts are found in all green plant parts

11. cuticle epidermis palisade mesophyll spongy mesophyll vascular bundle stomate Leaves Epidermis Mesophyll Vascular Bundles

12. cuticle epidermis palisade mesophyll spongy mesophyll vascular bundle stomate Leaves • Leaves have 3 main types of tissues: • Epidermis • Usually one cell thick and secrets a waxy cuticle to prevent water loss • Pores called stomata found in lower epidermis

13. cuticle epidermis palisade mesophyll spongy mesophyll vascular bundle stomate Leaves • Mesophyll • Most photosynthesis occurs here • Two layers of parenchyma cells • Palisade layer • Cell arrangement maximizes exposure to light • Spongy layer • Loose arrangement of cells leaving air spaces for gas exchange

14. cuticle epidermis palisade mesophyll spongy mesophyll vascular bundle stomate Leaves • Vascular Bundles • Transport system of the plants • Contains xylem (water transport) and phloem (sugar transport)

15. Opening/Closing Stomata • The guard cells (stomata) can be opened and closed to regulate gas exchange and minimize water loss in leaves Pore Chloroplast OPEN CLOSED Guard Cells

16. ATP ATP ATP ATP H2O H2O H+ H+ H+ H+ ATP ATP Opening Stomata Cell is now hypertonic to surroundings K+ • To open the stomata: • Potassium ions (K+) are actively pumped into the guard cells (uses ATP) • This causes the GCs to become hypertonic to their surroundings • Water is drawn into the GCs, increasing turgor pressure K+ K+ K+ K+ K+ CLOSED OPEN

17. ATP ATP ATP ATP ATP ATP Closing Stomata • To close the stomata: • K+ pumps deactivated allowing ions to diffuse out • Water drawn back out of the GC with the K+ ions • Decrease in turgor pressure makes GCs go limp (flacid) K+ K+ K+ K+ K+ K+ OPEN

18. H2O H+ H+ H+ H+ H2O Closing Stomata Cell is now hypotonic to surroundings • To close the stomata: • K+ pumps deactivated allowing ions to diffuse out • Water drawn back out of the GC with the K+ ions • Decrease in turgor pressure makes GCs go limp (flacid) K+ K+ K+ K+ K+ K+ OPEN

19. H2O H+ H+ H+ H+ H2O Closing Stomata • To close the stomata: • K+ pumps deactivated allowing ions to diffuse out • Water drawn back out of the GC with the K+ ions • Decrease in turgor pressure makes GCs go limp (flacid) CLOSED OPEN