2. AP BIOLOGY PHOTOSYNTHESIS Chapter 10 Light Reactions http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0076.JPG http://vilenski.org/science/safari/cellstructure/chloroplasts.html

3. Sunlight is made up of many different _______________ of light Your eyes “see” different wavelengths as different ___________ http://www.simontucket.com/_Portfolio/PortLarge/L_Il_Prism.jpg

4. A Look at Light The spectrum of color ROYGBIV

5. Plants gather the sun’s energy with light absorbing molecules called _________________. By: VanderWal

6. The main energy absorbing molecule in green plants is ___________________ ______________________________________ are pigments too. (These look orange, yellow, and brown) http://www.russianflora.com/store/images/product/custom_green_plant_35.jpg http://www.rnzih.org.nz/images/gardenimages/carrots_d.jpg

7. Light: absorption spectra Photosynthesis gets energy by absorbing wavelengths of light –chlorophyll a absorbs best in red & blue wavelengths & least in green –other pigments with different structures absorb light of different wavelengths

8. WHY ARE PLANTS GREEN? We “see” reflected light Light wavelengths that are reflected bounce back to your eyes... so leaves “LOOK” green. Image modified from: http://www.visibledreams.net/Web/color/color_3.html

9. WHY DON’T WE SEE THE OTHER PIGMENTS? Carotenoids are usually hidden by the presence of chlorophyll

10. In the fall chlorophyll production shuts down and other pigments “show” http://sps.k12.ar.us/massengale/ecology_notes_bi.htm http://www.litzsinger.org/weblog/archives/email%20AutumnTrees5%20LREC%20102605.jpg

11. PHOTOSYNTHESIS OVERVIEW Pearson Education Inc; Publishing as Prentice Hall

12. PHOTOSYNTHESIS HAPPENS IN CHLOROPLASTS = sac-like photosynthetic = stack of thylakoids membranes inside chloroplast Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing©2006

13. SPACES http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0076.JPG Gel-filled space Inside the thylakoid sac Gel-filled space inside chloroplast surrounding thylakoid sac Gel-filled space OUTSIDE chloroplast but inside the cell membrane

14. Pigments of photosynthesis Chlorophyll & other pigments –embedded in thylakoid membrane –arranged in a “photosystem” –structure-function relationship Why does this molecular structure make sense?

15. Phosphate groups Ribose Adenine ENERGY CARRIER = _____

16. P i ADP Energy for cellular work (Energy- consuming) Energy from catabolism (Energy- yielding) ATP +

17. High energy electron carrier = _____________ NADP + + 2e - + H + → NADPH

18. Photosynthesis Light reactions –light-dependent reactions –energy production reactions convert solar energy to chemical energy ATP & NADPH Calvin cycle –light-independent reactions –sugar production reactions uses chemical energy (ATP & NADPH) to reduce CO 2 & synthesize C 6 H 12 O 6 It ’ s the Dark Reactions!

19. Photosystems of photosynthesis 2 photosystems in thylakoid membrane –collections of chlorophyll molecules –act as light-gathering “antenna complex” –Photosystem II chlorophyll a P 680 = absorbs 680nm wavelength red light –Photosystem I chlorophyll b P 700 = absorbs 700nm wavelength red light reaction center antenna pigments

20. ETC of Photosynthesis Photosystem IIPhotosystem I

21. Light Dependent reactions Electron Transport Chain –membrane-bound proteins in organelle –electron acceptors NADPH –proton (H + ) gradient across inner membrane Where’s the double membrane? –ATP synthase enzyme H+H+ H+H+ H+

22. ETC of Photosynthesis  Chloroplasts transform light energy into chemical energy of ATP  use electron carrier NADPH

23. LIGHT DEPENDENT REACTIONS ETC produces from light energy –ATP & NADPH go to Calvin cycle PS II absorbs light –excited electron passes from chlorophyll to “primary electron acceptor” –need to replace electron in chlorophyll –enzyme extracts electrons from H 2 O & supplies them to chlorophyll splits H 2 O O combines with another O to form O 2 O 2 released to atmosphere and we breathe easier!

24. ETC of Photosynthesis H+H+ H+H+ 1 3 4 H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP to the Calvin Cycle

25. 1 2 H+H+ H+H+ 3 4 H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP ETC of Photosynthesis to the Calvin Cycle

26. ETC of Photosynthesis 6 5 $$ in the bank… reducing power to the Calvin Cycle electron carrier

27. ETC of Photosynthesis split H 2 O

28. MAKING ATP moves the electrons runs the pump pumps the protons forms the gradient drives the flow of protons through ATP synthase attaches P i to ADP forms the ATP H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP

29. Noncyclic Photophosphorylation Light reactions elevate electrons in 2 steps (PS II & PS I) –PS II generates energy as ATP –PS I generates reducing power as NADPH

30. Cyclic photophosphorylation If PS I can’t pass electron to NADP… it cycles back to PS II & makes more ATP, but no NADPH –coordinates light reactions to Calvin cycle –Calvin cycle uses more ATP than NADPH X

31. Photophosphorylation noncyclic photophosphorylation cyclic photophosphorylation

32. 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ Experimental evidence Where did the O 2 come from? –radioactive tracer = O 18 6CO 2 6H 2 O C 6 H 12 O 6 6O26O2 light energy  +++ Experiment 1 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ Experiment 2 Proved O 2 came from H 2 O not CO 2 = plants split H 2 O

33. LIGHT DEPENDENT REACTION Requires ______________ Molecules embedded in ________________________ Made up of __________________ connected by ______________________ & ___________________ Uses light energy to change ADP + P → _______ NADP + + 2e - + H + → _________ Breaks apart ______ molecules and releases _____________

34. PHOTOSYNTHESIS