1. Copyright © 2009 Pearson Education, Inc. PowerPoint Lectures for Biology: Concepts & Connections, Sixth Edition Campbell, Reece, Taylor, Simon, and Dickey Chapter 7 Photosynthesis: Using Light to Make Food Lecture by Richard L. Myers

2. Carbon dioxide C 6 H 12 O 6 Photosynthesis H2OH2O CO 2 O2O2 Water + 66 Light energy Oxygen gas Glucose + 6

3. AN OVERVIEW OF PHOTOSYNTHESIS Copyright © 2009 Pearson Education, Inc.

4. 7.1 Autotrophs are the producers of the biosphere  Autotrophs - able to make their own food –plants, algae and other protists, and some prokaryotes –Some use light, some use chemicals Copyright © 2009 Pearson Education, Inc.

5. 7.1 Autotrophs are the producers of the biosphere –Chloroplasts - organelles consisting of photosynthetic pigments, enzymes, and molecules grouped together in membranes – site of photosynthesis Copyright © 2009 Pearson Education, Inc.

10. 7.2 Photosynthesis occurs in chloroplasts in plant cells –Chlorophyll  light absorbing pigment  responsible for the green color of plants  converts solar energy to chemical energy Copyright © 2009 Pearson Education, Inc.

11. 7.2 Photosynthesis occurs in chloroplasts in plant cells  Found in the mesophyll, the green tissue in the interior of the leaf  Stomata -tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit  Veins in the leaf deliver water absorbed by roots Copyright © 2009 Pearson Education, Inc.

12. CO 2 O2O2 Stoma Mesophyll Cell Vein Chloroplast Mesophyll Leaf Cross Section Leaf

14. 6 CO 2 + 12 H 2 O Experiment 1 C 6 H 12 O 6 + 6 H 2 O + 6 O 2 Not labeled 6 CO 2 + 12 H 2 O Experiment 2 C 6 H 12 O 6 + 6 H 2 O + 6 O 2 Labeled

15. 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 Reduction Oxidation

16. 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 Reduction Oxidation

17. THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY Copyright © 2009 Pearson Education, Inc.

18. Wavelength (nm) 10 –5 nm Increasing energy Visible light 650 nm 10 –3 nm 1 nm10 3 nm10 6 nm 1 m 10 3 m 380 400 500 600700 750 Radio waves Micro- waves Infrared X-rays UV Gamma rays

19. Copyright Pearson Prentice Hall Light and Pigments  Chlorophyll does not absorb light well in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green. Estimated Absorption (%) 100 80 60 40 20 0 400 450 500 550 600 650 700 750 Chlorophyll b Chlorophyll a Wavelength (nm)

20. Light Chloroplast Thylakoid Absorbed light Transmitted light Reflected light

21. 7.7 Photosystems capture solar power  Pigments in chloroplasts are responsible for absorbing photons (capturing solar power), causing release of electrons Copyright © 2009 Pearson Education, Inc.

22. Chlorophyll molecule Excited state Ground state Heat Photon (fluorescence) e–e–

23. 7.7 Photosystems capture solar power  The energy released is conserved as it is passed from one molecule to another molecule- called photosystems. Copyright © 2009 Pearson Education, Inc.

24. 7.7 Photosystems capture solar power  Two types of photosystems have been identified and are called photosystem I and photosystem II Copyright © 2009 Pearson Education, Inc.

25. 7.8 Two photosystems connected by an electron transport chain generate ATP and NADPH  During the light reactions, light energy is transformed into the chemical energy of ATP and NADPH –electrons removed from water pass from photosystem II to photosystem I and are accepted by NADP + –The bridge between photosystems II and I is an electron transport chain that provides energy for the synthesis of ATP Copyright © 2009 Pearson Education, Inc.

26. 7.8 Two photosystems connected by an electron transport chain generate ATP and NADPH  NADPH, ATP, and O 2 are the products of the light reactions – called the light dependent reactions Copyright © 2009 Pearson Education, Inc.

27. 7.9 Chemiosmosis powers ATP synthesis in the light reactions  Photosynthesis creates concentration gradient of H+ ions which powers the production of ATP Copyright © 2009 Pearson Education, Inc.

28. 7.9 Chemiosmosis powers ATP synthesis in the light reactions  ATP synthase couples the flow of H + to the phosphorylation of ADP –The chemiosmotic production of ATP in photosynthesis is called photophosphorylation Copyright © 2009 Pearson Education, Inc.

29. + O2O2 H2OH2O 1212 H+H+ NADP + H+H+ NADPH + 2 H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ Photosystem II Photosystem I Electron transport chain ATP synthase Light Stroma (low H + concentration) Chloroplast Thylakoid membrane Thylakoid space (high H + concentration) ADP + PATP

30. THE CALVIN CYCLE: CONVERTING CO 2 TO SUGARS Copyright © 2009 Pearson Education, Inc.

31. 7.10 ATP and NADPH power sugar synthesis in the Calvin cycle  The Calvin cycle makes sugar within a chloroplast –Need CO 2 –ATP –NADPH –Called the light independent cycle Copyright © 2009 Pearson Education, Inc.

32. NADPH ATP RuBP 3 P G3P P Input: CO 2 1 Rubisco 3 P Step Carbon fixation 3-PGA 6 P C ALVIN CYCLE 6 6 6 6 P Step Reduction 2 2 G3P 5 P 3 3 1 P Glucose and other compounds Output: Step Release of one molecule of G3P 1 Step Regeneration of RuBP 4 4 ATP 3 3 ADP NADP + 6 ADP +

33. PHOTOSYNTHESIS REVIEWED AND EXTENDED Copyright © 2009 Pearson Education, Inc.

34. NADP + NADPH ATP CO 2 + H2OH2O ADP P Electron transport chains Thylakoid membranes Light Chloroplast O2O2 C ALVIN C YCLE (in stroma) Sugars Photosystem II Photosystem I L IGHT R EACTIONS RuBP 3-PGA C ALVIN C YCLE Stroma G3P Cellular respiration Cellulose Starch Other organic compounds

35. 7.12 EVOLUTION CONNECTION: Adaptations that save water in hot, dry climates evolved in C 4 and CAM plants  Some plants have evolved a means of carbon fixation that saves water during photosynthesis –C 4 plants because they first fix carbon dioxide into a four-carbon compound – (sugar cane, corn, some grasses) –CAM – open stomata at night (cactus and pineapple)- crassulacean acid metabolism Copyright © 2009 Pearson Education, Inc.

36. PHOTOSYNTHESIS, SOLAR RADIATION, AND EARTH’S ATMOSPHERE Copyright © 2009 Pearson Education, Inc.

37. 7.13 CONNECTION: Photosynthesis moderates global warming  The greenhouse effect results from solar energy warming our planet  Global warming – the steady rise in temperature of the earth caused by increasing amount of greenhouse gases Copyright © 2009 Pearson Education, Inc.

39. Atmosphere Sunlight Some heat energy escapes into space Radiant heat trapped by CO 2 and other gases

40. 7.14 TALKING ABOUT SCIENCE: Mario Molina talks about Earth’s protective ozone layer –Ozone provides a protective layer (the ozone layer) in our atmosphere to filter out powerful ultraviolet radiation –industrial chemicals called chlorofluorocarbons, or CFCs, deplete the ozone layer Copyright © 2009 Pearson Education, Inc.

41. Southern tip of South America Antarctica