2. AP Biology 2007-2008

3. AP Biology Photosynthesis: Life from Light and Air

4. AP Biology The energy needs of life consumers producers  All life needs a constant input of energy  Heterotrophs (Animals)  get their energy from “eating others”  eat food (other organisms) = organic molecules  make energy through respiration  Autotrophs (Plants)  produce their own energy (from “self”)  convert energy of sunlight  build organic molecules (CHO) from CO 2  make energy & synthesize sugars through photosynthesis. Make additional ATP through respiration.

5. AP Biology How are they connected? glucose + oxygen  carbon + water + energy dioxide C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP  +++ Heterotrophs + water + energy  glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ Autotrophs making energy & organic molecules from light energy making energy & organic molecules from ingesting organic molecules oxidation = exergonic reduction = endergonic But remember autotrophs do cell resp. also!

6. AP Biology N P K … H2OH2O What does it mean to be a plant  Need to…  collect light energy  transform it into chemical energy  store light energy  in a stable form to be moved around the plant or stored  need to get building block atoms from the environment  C,H,O,N,P,K,S,Mg  produce all organic molecules needed for growth  carbohydrates, proteins, lipids, nucleic acids ATP glucose CO 2

7. AP Biology Plant structure  Obtaining raw materials  sunlight  leaves = solar collectors  CO 2  stomates = gas exchange H2OH2O  uptake from roots  nutrients  N, P, K, S, Mg, Fe…  uptake from roots

8. AP Biology stomate transpiration gas exchange

9. AP Biology Chloroplasts chloroplasts in plant cell cross section of leaf leaves chloroplast absorb sunlight & CO 2 make energy & sugar chloroplasts contain chlorophyll CO 2

10. AP Biology  Chloroplasts  double membrane  stroma - fluid-filled interior  thylakoid  grana stacks  Thylakoid membrane contains  chlorophyll molecules  electron transport chain  ATP synthase  H + gradient built up in thylakoid lumen Plant structure outer membrane inner membrane thylakoid granum stroma

11. AP Biology Pigments of photosynthesis  Chlorophylls & other pigments  embedded in thylakoid membrane  arranged in a “photosystem”  collection of molecules

12. AP Biology Light  The spectrum of color ROYGBIV

13. AP Biology Light: absorption spectra  Photosynthesis gets energy by absorbing wavelengths of light  chlorophyll a  absorbs best in red & blue wavelengths & least in green  accessory pigments with different structures absorb light of different wavelengths  chlorophyll b, carotenoids, xanthophylls Why are plants green?

14. AP Biology Photosynthesis 1. Light Reactions  light-dependent reactions  energy conversion reactions  convert solar energy to chemical energy (ATP & NADPH) 2. Calvin Cycle  light-independent reactions  sugar building reactions  uses chemical energy (ATP & NADPH) to reduce CO 2 & synthesize C 6 H 12 O 6 It ’ s not the Dark Reactions!

15. AP Biology Photosynthesis: The Light Reactions

16. AP Biology  Electron Transport Chain  like in cellular respiration  proteins in organelle membrane  electron acceptors  NADPH  proton (H + ) gradient across inner membrane  ATP synthase enzyme Light reactions 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+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP thylakoid chloroplast

17. AP Biology Mitochondria transfer chemical energy from food molecules into chemical energy of ATP  use electron carrier NADH ETC of Respiration generates H 2 O

18. AP Biology ETC of Photosynthesis Chloroplasts transform light energy into chemical energy of ATP  use electron carrier NADPH generates O 2

19. AP Biology Generating ATP  moves the electrons  runs the pump  pumps the protons  builds the gradient  drives the flow of protons through ATP synthase  bonds P i to ADP  generates the ATP sunlightbreakdown of C 6 H 12 O 6 respirationphotosynthesis H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP

20. AP Biology Photosystems  2 photosystems in thylakoid membrane  collections of chlorophyll molecules  act as light-gathering molecules  Photosystem II  P 680 chlorophyll = absorbs 680nm wavelength red light  Photosystem I  P 700 chlorophyll= absorbs 700nm wavelength red light photosystem

21. AP Biology ETC of Photosynthesis Photosystem IIPhotosystem I

22. AP Biology ETC of Photosynthesis

23. AP Biology 1 ETC of Photosynthesis e e sun Photosystem II P680

24. AP Biology 1 2 ETC of Photosynthesis Photosystem II P680 O HH H H e e e-e- e-e- 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+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP thylakoid chloroplast H+H+ +H+H O O Plants SPLIT water! fill the e – vacancy get pumped into tylakoid lumen to form H+ gradient e e

25. AP Biology 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+ e e e e ATP to Calvin Cycle energy to build carbohydrates 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+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP thylakoid chloroplast Photosystem II P680 ETC of Photosynthesis ATP

26. AP Biology e e e e sun 5 Photosystem II P680 Photosystem I P700 e e ETC of Photosynthesis e e fill the e – vacancy

27. AP Biology 6 electron carrier e e e e 5 sun NADPH to Calvin Cycle Photosystem II P680 Photosystem I P700 ETC of Photosynthesis

28. AP Biology split H 2 O ETC of Photosynthesis O ATP to Calvin Cycle H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ e e e e sun

29. AP Biology ETC of Photosynthesis  ETC uses light energy to produce  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

30. AP Biology 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++ Experimental evidence  Where does the O 2 come from?  Use 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!

31. AP Biology Non-Cyclic Electron Transport  Light reactions elevate electrons in 2 steps (PS II & PS I)  PS II generates energy as ATP  PS I generates reducing power as NADPH ATP

32. AP Biology Non-Cyclic Electron Transport

33. AP Biology Cyclic Electron Transport  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  ATP

34. AP Biology Cyclic Electron Transport

35. AP Biology Non-Cyclic Electron Transport (Photophosphorylation) NONcyclic photophosphorylation ATP NADP

36. AP Biology Cyclic Electron Transport (Photophosphorylation) cyclic photophosphorylation ATP

37. AP Biology Characteristics of the Light Reactions 1. Energy from light is used to split water into H and O. 2. O 2 is given off as a waste product and exits through stomata. 3. Electron transport chain creates H + gradient that is used to make ATP (for later use in Calvin Cycle). 4. H and electrons are carried by NADPH to the Calvin Cycle.

38. AP Biology Photosynthesis: The Calvin Cycle

39. AP Biology The Calvin Cycle Whoops! Wrong Calvin… 1950s | 1961

40. AP Biology Remember what it means to be a plant…  Need to produce all organic molecules necessary for growth  carbohydrates, lipids, proteins, nucleic acids  Need to store chemical energy (ATP) produced from light reactions  in a more stable form  that can be moved around plant  saved for a rainy day + water + energy  glucose + oxygen carbon dioxide 6CO 2 6H 2 O C 6 H 12 O 6 6O 2 light energy  +++

41. AP Biology Light reactions  Convert solar energy to chemical energy  ATP  NADPH  What can we do now?  energy  reducing power   build stuff !! photosynthesis ATP

42. AP Biology How is that helpful?  Want to make C 6 H 12 O 6  synthesis  How? From what? What raw materials are available? CO 2 C 6 H 12 O 6 NADPH NADP reduces CO 2 carbon fixation NADP

43. AP Biology From CO 2  C 6 H 12 O 6  CO 2 has very little chemical energy  fully oxidized  C 6 H 12 O 6 contains a lot of chemical energy  highly reduced  Synthesis (anabolic) = endergonic  put in a lot of energy  Reduction of CO 2  C 6 H 12 O 6 proceeds in many small uphill steps  each catalyzed by a specific enzyme  using energy stored in ATP & NADPH made from the light reactions

44. AP Biology From Light Reactions to Calvin Cycle  Calvin cycle occurs in the chloroplast stroma  Need products of light reactions to drive synthesis reactions  ATP  NADPH stroma thylakoid ATP

45. AP Biology starch, sucrose, cellulose & more 1C CO 2 Calvin Cycle 5C RuBP 3C RuBisCo 1. Carbon fixation 2. Reduction 3. Regeneration of RuBP ribulose 1,5-bisphosphate ribulose bisphosphate carboxylase 6 NADP 6 NADPH 6 ADP 6 ATP 3 ADP 3 ATP used to make glucose 3C G3P glyceraldehyde 3-phosphate CCCCCCCCCCCCCCC 6C CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC 3PG 3-phosphoglycerate CCCCCCCCCCCCCCCCCCCCC C C C CCC == | H | H | H | H | H | H CCC –– 5C compare this diagram with 6.21

46. AP Biology In Principles of Life, PGA is known as 3PG. In Principles of Life, PGAL is known as G3P.

47. AP Biology G3P  Glyceraldehyde 3-Phosphate  end product of Calvin Cycle  energy rich 3 carbon sugar  G3P is an important intermediate  G3P   glucose   carbohydrates   lipids   phospholipids, fats, waxes   amino acids   proteins   nucleic acids   DNA, RNA

48. AP Biology RuBisCo  Enzyme which fixes carbon from air (step 1 in Calvin Cycle)  ribulose bisphosphate carboxylase  the most important enzyme in the world!  it makes life out of air!  definitely the most abundant enzyme

49. AP Biology Accounting  The accounting is complicated  6 turns of Calvin cycle = 2 G3P  6 CO 2  2 G3P (3C)  6 turns of Calvin cycle = 1 C 6 H 12 O 6 (6C)  6 CO 2  1 C 6 H 12 O 6 (6C)  18 ATP + 12 NADPH  1 C 6 H 12 O 6  any ATP left over from light reactions will be used elsewhere by the cell

50. AP Biology Characteristics of the Calvin Cycle 1. CO 2 enters through the stomates. 2. Hydrogen is released from its electron-carrier (NADPH) and is bound to CO 2 to make glucose. 3. Large amounts of energy (ATP) are needed for reactions to occur. 4. Each stage needs specific enzymes.

51. AP Biology Photosynthesis Summary  Light reactions  produced ATP  produced NADPH  consumed H 2 O  produced O 2 as byproduct  Calvin cycle  consumed CO 2  produced G3P (sugar)  regenerated ADP  regenerated NADP NADPADP

52. AP Biology Light Reactions O2O2 H2OH2O Energy Building Reactions ATP  produces ATP  produces NADPH  releases O 2 as a waste product sunlight H2OH2O ATP O2O2 light energy  +++ NADPH

53. AP Biology Calvin Cycle sugars CO 2 Sugar Building Reactions ADP  builds sugars  uses ATP & NADPH  recycles ADP & NADP  back to make more ATP & NADPH ATP NADPH NADP CO 2 C 6 H 12 O 6  +++ NADPATP + NADPHADP

54. AP Biology Putting it all together CO 2 H2OH2OC 6 H 12 O 6 O2O2 light energy  +++ Sugar Building Reactions Energy Building Reactions Plants make both:  energy  ATP & NADPH  sugars sunlight O2O2 H2OH2O sugars CO 2 ADP ATP NADPH NADP

55. AP Biology

56. H2OH2O Energy cycle Photosynthesis Cellular Respiration sun glucose O2O2 CO 2 plants animals, plants ATP The Great Circle of Life,Mufasa! CO 2 H2OH2O C 6 H 12 O 6 O2O2 light energy  +++ even though this equation is a bit of a lie … it makes a better story CO 2 H2OH2O C 6 H 12 O 6 O2O2 ATP energy  +++

57. AP Biology Summary of photosynthesis  Where did the CO 2 come from?  Where did the CO 2 go?  Where did the H 2 O come from?  Where did the H 2 O go?  Where did the energy come from?  What’s the energy used for?  What will the C 6 H 12 O 6 be used for?  Where did the O 2 come from?  Where will the O 2 go?  What else is involved…not listed in this equation? 6CO 2 6H 2 OC 6 H 12 O 6 6O 2 light energy  +++

58. AP Biology Supporting a biosphere  On global scale, photosynthesis is the most important process for the continuation of life on Earth  each year photosynthesis…  captures 121 billion tons of CO 2  synthesizes 160 billion tons of carbohydrate  heterotrophs are dependent on plants as food source for fuel & raw materials

59. AP Biology The poetic perspective…  All the solid material of every plant was built by sunlight out of thin air  All the solid material of every animal was built from plant material Then all the plants, cats, dogs, elephants & people … are really particles of air woven together by strands of sunlight! sun air