Ch6 PHOTOSYNTHESIS (rap) CO2 + H2O --sun--> C6H12O6 + O

1. Ch6 PHOTOSYNTHESIS (rap) CO2 + H2O --sun--> C6H12O6 + O

2. Examples of Photoautotrophs • Capture sunlight energy and use it to carry out photosynthesis • Phytoplankton - the first step in ocean food chains • Plants • Some bacteria • Many protistans

3. 2 types of organisms: • autotrophs • Carbon source is: • Energy source is: • Heterotrophs • Carbon + Energy source are: carbon dioxide sunlight autotrophs! yum

4. Photosynthesis SUN energy SUGAR energy Cellular Respiration SUGAR energy ATP energy

6. Photosynthesis Equation LIGHT ENERGY 6O2 + C6H12O6 + 6H2O 12H2O + 6CO2 oxygen glucose water water carbon dioxide (note: copy on top of pp)

7. Let’s Balance This Equation ! 6 6 6 ___CO2 + ___H20  ___C6H12O6 + ___O2 The product of photosynthesis is GLUCOSE

8. inputs and outputs of the photosynthetic process. H20

10. Can affect rate of Photosynthesis Amount of Carbon Light Temperature

11. Leaves and Leaf Structure • Plants are the only photosynthetic organisms to have _______ (and not all plants have leaves). • A leaf may be viewed as a solar collector crammed full of photosynthetic cells. leaves

12. Leaf Structure UPPER EPIDERMIS cuticle PALISADE MESOPHYLL xylem SPONGY MESOPHYLL phloem LOWER EPIDERMIS AIR SPACES CO2 one stoma O2

13. Tiny pores UNDER leaf  Stomata CO2 • Allows ____________ in • Allows ___________ out • Allows___________ out K+ and H20 O2 H2O <<LINK>> K+ and H20

15. What Causes Stomata to Open? to open: to close:

17. A. CHLOROPLAST STRUCTURE • The number of chloroplasts in a cell varies from 20 – 100. • THIS IS THE ORGANELLE THAT DOES PHOTOSYNTHESIS

18. Chloroplasts Organelles of photosynthesis stroma Two membranes granum thylakoid

19. thylakoid • What is the structural unit of photosynthesis? • WHERE LIGHT REACTION TAKES PLACE • Thylakoids are stacked like pancakes in stacks known collectively as . • The aeas between grana are referred to as? DARK REACTION TAKES PLACE HERE grana stroma

20. STROMA THYLAKOID GRANA INTERMEMBRANE INNER OUTER

22. A. THE NATURE OF LIGHT • Green plants use sunlight for photosynthesis Light energy is in form of . Light travels in “bundles” called What IS sunlight??? • Sunlight = mixture of different wavelengths of light; many are visible to the eye (VISIBLE LIGHT SPECTRUM). wavelengths photons

24. Electromagnetic Spectrum Shortest Most Gamma rays wavelength energy X-rays UV radiation Visible light Infrared radiation Microwaves Longest Least Radio waves wavelength energy

25. Visible Light long waves short waves low energy high energy 10-5nm 10-3nm 1nm 103nm 106nm 109nm 1 m 103m V I B G Y O R

26. So, what IS a pigment?? • Molecules that have evolved to absorb wavelengths in the visible region of the spectrum very well

27. Chlorophyll • ________________,the green pigment common to all photosynthetic cells • absorbs all wavelengths of visible light EXCEPT GREEN, which it REFLECTS to be detected by our eyes. • Black pigments all of the wavelengths that strike them. • White pigments/lighter colors all or almost all of the energy striking them. absorb reflect

28. CHLOROPHYLL - pigment found in green plant Chlorophyll a – (primary pigment); directly involved in the light dependent reactions Chlorophyll b - (accessory pigment); helps capture sunlight and transfer energy to chlorophyll a

29. a) Chlorophyll does not absorb most yellow and green light – these colors are reflected b) Chlorophyll b absorbs light with wavelengths of 480 nm (blue) and 650 nm (red) (more blue/less red) c) Chlorophyll a - absorbs light within wavelengths of 435 nm (blue) and 675 nm (red) (less blue/more red than Chl.b)

31. 4. ACCESSORY Pigments - Pass their absorbed sunlight energy to chlorophyll, which passes the energy to the photosynthetic pathway. For this reason they are called “accessory” pigments Carotenoids – carotene & Xanthophylls Anthocyanins Phycobilins

32. Why do plants need accessory pigments? • To utilize ALL wavelengths of light entering plant

33. a) Carotene – reflect yellow, red and orange; 450 nm and 500 nm; absorb blue and green. They are not water soluble. Found in carrots, oranges and autumn leaves

34. b) Xanthyphylls – reflect yellow and orange c)Anthocyanins - responsible for the red, purple, and blue colors of many fruits, vegetables, cereal grains, and flowers.

35. Overview of Photosynthesis equation: 6CO2 + 12H2O ----------> C6H12O6+ 6O2 + 6H2O Chlorophyll Light In two stages. . .

37. Stage 1 – Light Dependent Reactions Water is split into hydrogen ions (H+), electrons and oxygen (O2) The O2diffuses out of the chloroplasts (by-product) The light energy is converted to chemical energy, which is temporarily stored in ATP and NADPH

38. Stage 2 – Calvin Cycle(light independent rxn) The chemical energy stored in ATP and NADPH powers the formation of organic compounds (sugars), using carbon dioxide (CO2)

39. (thylakoid membrane) The Light Reactions occur in the the Dark Reactions occur in the stroma

40. A. Light Dependent Reaction 1. splits H2O into H+ (proton), electron(-) and O2 2. forms ATP 3. forms NADPH 4. releases O2

41. Action of Photosystem I And II

42. chlorophyll • Light energy strikes the: Electrons of specialized chlorophyll molecules in Photosystem (Ps II) absorb the energy and become “ ” (raised to a higher energy level. • The high energy electrons leave the chlorophyll and travel to a: primary electron acceptor. excited

43. electron transport chain • The primary acceptor donates the electrons to a series of molecules (electron acceptors) in an . As they do, the energy level of the electrons is reduced. The energy released is used to move into the thylakoids. 4. At the same time, Photosystem I (Ps I) absorbs light energy, raising the energy level of the electrons in chlorophyll again. These electrons are replaced by the electrons from Photosystem II (Ps II). H+

44. 5. These “excited” electrons are passed to a different primary electron acceptor and then through another ETC. These electrons are moved to the stroma side of the membrane. 6. The energy and electrons are then combined with a H+ proton and NADP+ forming NADPH

45. Pigments in a Photosystem reaction center (a specialized chlorophyll a molecule)

46. water • The electrons from Photosystem I & II must be replaced. The source of electrons is the splitting of (HYDROLYSIS): 2 H2O 4 H+ + 4 e- + O2 What happens to the oxygen?? released into atmosphere

47. NADPH NADP+ + H+ H+ H+ H+

48. PRODUCTION OF ATP = A process called chemiosmosis 8. Chemiosmosis relies on a concentration gradient of protons(H+) across the thylakoid membrane. 9. Where do we get these H+ protons?? • produced from: • other protons are pumped into the thylakoid the breakdown of water molecules

49. 10. Both these mechanisms act to build up a concentration gradient of protons (H+). The concentration of protons (H+) is higher in the ____________________ than in the stroma. 11. The protons (H+) can only pass through special protein channels of ATP synthase, thus converting ADP + P to __________ thylakoid ATP