Uploaded byDr. Pranabjyoti Das
Photosynthesis
Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. It occurs in two stages - the light-dependent reactions where light energy is captured to form ATP and NADPH using chlorophyll, and the light-independent reactions of the Calvin cycle where carbon dioxide is incorporated into organic compounds to form glucose using ATP and NADPH. Photosynthesis provides the primary source of energy and organic molecules that sustain life on Earth and produces oxygen as a byproduct.
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Photosynthesis
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- 2. • Almost allplants are photosynthetic. Even some bacteria and protists are also photosynthetic. – Autotrophs generate their own organic matter (food) by photosynthesis Mosses & ferns Euglena Cyanobacteria THE BASICS OF PHOTOSYNTHESIS 5/19/2021 2 Arunodoi Junior College
- 3. Why is Photosynthesisimportant? Makes organic molecules (glucose) out of inorganic materials carbon dioxide and water. It begins all food chains and food webs. Thus all life is supported by photosynthesis. 5/19/2021 3 Arunodoi Junior College It also makes oxygen gas for all !!
- 4. Photosynthesis starts toecological food webs ! 5/19/2021 4 Arunodoi Junior College
- 5. A Stomata 5/19/2021 ArunodoiJunior College 5
- 6. Why Are PlantsGreen ? 5/19/2021 6 Arunodoi Junior College Plants are green due to presence of Chlorophyll Chlorophyll are some chemicals present in the thyllakoid membrane of each Granum Grana are found suspended in the Stroma of the Chloroplasts Besides Chloroplasts plants have other pigments such as Chromoplasts and Leukoplasts
- 7. A Chloroplast 5/19/2021 ArunodoiJunior College 7
- 8. Electromagnetic Spectrum and VisibleLight Gamma rays X-rays UV Infrared & Microwaves Radio waves Visible light Wavelength (nm) 5/19/2021 8 Arunodoi Junior College
- 9. Sunlight minus absorbed wavelengthsor colors equals the apparent color of an object. The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. 5/19/2021 9 Arunodoi Junior College
- 10. Why are plantsgreen? Transmitted light 5/19/2021 10 Arunodoi Junior College
- 11. Chloroplasts absorb only the REDand BLUE spectra of sunlight and convert them to chemical energy, ATP Light Reflected light Absorbed light Transmitted light Chloroplast 5/19/2021 11 Arunodoi Junior College Only Red and Blue Colour has the Magic Show
- 12. PHOTOSYNTHESIS Absorbing Light Energyto make chemical energy: Glucose ! Pigments: Absorb different colors of white light (VIBGYOR) •Main pigment: Chlorophyll a •Accessory pigments: Chlorophyll b and Carotenoids •These pigments absorb all wavelengths (light) BUT not green! 5/19/2021 12 Arunodoi Junior College
- 13. In most plants,photosynthesis occurs primarily in the leaves, in the chloroplasts A chloroplast contains: a) Stroma, b)Grana, the stacks of thylakoids The thylakoids contain chlorophyll – Chlorophyll is the green pigment that captures light for photosynthesis Photosynthesis occurs in chloroplasts 5/19/2021 13 Arunodoi Junior College
- 14. The location andstructure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid Thylakoid Stroma Granum Stroma Grana 5/19/2021 14 Arunodoi Junior College
- 15. Excited state e Heat Light Photon Light (fluorescence) Chlorophyll molecule Ground state 2 (a) Absorption ofa photon Excitation of chlorophyll in a chloroplast Loss of energy due to heat causes the photons of light to be less energetic. Less energy translates into longer wavelength. Energy = (Planck’s constant) x (velocity of light)/(wavelength of light) Transition toward the red end of the visible spectrum. e 5/19/2021 15 Arunodoi Junior College
- 16. Cyclic Photophosphrylation 5/19/2021 ArunodoiJunior College 16
- 17. Non-Cyclic Photophosphorylation 5/19/2021 ArunodoiJunior College 17
- 18. Photosynthesis is theprocess by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water AN OVERVIEW OF PHOTOSYNTHESIS PHOTOSYNTHESIS 5/19/2021 18 Arunodoi Junior College
- 19. The Calvin cyclemakes sugar from carbon dioxide ATP generated by the light reactions provides the energy for sugar synthesis The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light Chloroplast Light reactions Calvin cycle NADP ADP + P The light reaction convert solar energy to chemical energy and Produces ATP & NADPH AN OVERVIEW OF PHOTOSYNTHESIS 5/19/2021 19 Arunodoi Junior College
- 20. Oxygen and Sugar! 5/19/202120 Arunodoi Junior College
- 21. 5/19/2021 21 Arunodoi JuniorCollege Photosynthesis : As a whole
- 22. EQUATION FOR PHOTOSYNTHESIS 6CO2 +6H2O + ENERGY C6H12O6 + 6O2 CARBON DIOXIDE WATER GLUCOSE OXYGEN 5/19/2021 22 Arunodoi Junior College
- 23. Oxidation Reaction • Theloss of electrons from a substance. • Or the gain of oxygen. glucose 6CO2 + 6H2O C6H12O6 + 6O2 Oxidation 5/19/2021 23 Arunodoi Junior College
- 24. Reduction Reaction • Thegain of electrons to a substance. • Or the loss of oxygen. glucose 6CO2 + 6H2O C6H12O6 + 6O2 Reduction 5/19/2021 24 Arunodoi Junior College
- 25. PHOTOSYNTHESIS • 2 Phases –Light-dependent reaction – Light-independent reaction • Light-dependent: converts light energy into chemical energy; produces ATP and NADPH molecules to be used to fuel light-independent reaction • Light-independent: uses ATP produced to make simple sugars/ glucose 5/19/2021 25 Arunodoi Junior College
- 26. PHOTOSYNTHESIS • Light-dependent reaction(LIGHT Reaction) – Requires light – Occurs in chloroplast (in thylakoids) – Chlorophyll (thylakoid) traps energy from light – Light excites electron (e-) •Kicks e- out of chlorophyll to an electron transport chain •Electron transport chain: series of proteins in thylakoid membrane 5/19/2021 26 Arunodoi Junior College
- 27. PHOTOSYNTHESIS • Light-dependent reaction(LIGHT Reaction) – Energy lost along electron transport chain – Lost energy used to recharge ATP from ADP – NADPH produced from e- transport chain •Stores energy until transfer to stroma •Plays important role in light-independent reaction – Total byproducts: ATP, NADP, O2 5/19/2021 27 Arunodoi Junior College
- 28. 1. Light Reaction(Electron Flow) • During the light reaction, there are two possible routes for electron flow. A. Cyclic Electron Flow B. Noncyclic Electron Flow 5/19/2021 28 Arunodoi Junior College
- 29. Water-splitting photosystem NADPH-producing photosystem ATP mill Two types of photosystem scooperate in the light reactions 5/19/2021 29 Arunodoi Junior College
- 30. A. Cyclic ElectronFlow • Occurs in the thylakoid membrane. • Uses Photosystem I only • P700 reaction center- chlorophyll a • Uses Electron Transport Chain (ETC) • Generates ATP only ADP + ATP P 5/19/2021 30 Arunodoi Junior College Reaction Centre
- 31. 1) Cyclic ElectronFlow P700 Primary Electron Acceptor e- e- e- e- ATP produced by ETC Photosystem I Accessory Pigments SUN Photons 5/19/2021 31 Arunodoi Junior College
- 32. 2) Noncyclic ElectronFlow • Occurs in the thylakoid membrane • Uses PS II and PS I • P680 rxn center (PSII) - chlorophyll a • P700 rxn center (PS I) - chlorophyll a • Uses Electron Transport Chain (ETC) • Generates O2, ATP and NADPH 5/19/2021 32 Arunodoi Junior College
- 33. Noncyclic Electron Flow P700 PhotosystemI P680 Photosystem II Primary Electron Acceptor Primary Electron Acceptor ETC Enzyme Reaction H2O 1/2O2 + 2H+ ATP NADPH Photon 2e- 2e- 2e- 2e- 2e- SUN Photon 5/19/2021 33 Arunodoi Junior College
- 34. Noncyclic Electron Flow •ADP + ATP • NADP+ + H NADPH • Oxygen comes from the splitting of H2O, not CO2 H2O 1/2 O2 + 2H+ (Reduced) P (Reduced) (Oxidized) 5/19/2021 34 Arunodoi Junior College
- 35. Primary electron acceptor Primary electron acceptor Photons PHOTOSYSTEMI PS II Energy for synthesis of Noncyclic Photophosphorylation 5/19/2021 35 Arunodoi Junior College
- 36. • The O2liberated by photosynthesis is made from the oxygen in water (H+ and e-) Plants produce O2 gas by splitting H2O 5/19/2021 36 Arunodoi Junior College
- 37. 2 H +1/2 Water-splitting photosystem Reaction- center chlorophyll Light Primary electron acceptor Energy to make Primary electron acceptor Primary electron acceptor NADPH-producing photosystem Light NADP 1 2 3 How the Light Reactions Generate ATP and NADPH 5/19/2021 37 Arunodoi Junior College
- 38. PHOTOSYNTHESIS • Light-independent reaction(Dark Reaction) – Does not require light – Calvin Cycle •Occurs in stroma of chloroplast •Requires CO2 •Uses ATP and NADPH as fuel to run •Makes glucose sugar from CO2 and Hydrogen 5/19/2021 38 Arunodoi Junior College
- 39. Calvin Cycle • CarbonFixation (light independent rxn). • C3 plants (80% of plants on earth). • Occurs in the stroma. • Uses ATP and NADPH from light rxn. • Uses CO2. • To produce glucose: it takes 6 turns and uses 18 ATP and 12 NADPH. 5/19/2021 39 Arunodoi Junior College
- 40. Chloroplast Granum Thylakoid Stroma Outer Membrane Inner Membrane 5/19/202140 Arunodoi Junior College
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- 44. • A PhotosynthesisRoad Map Chloroplast Light Stack of thylakoids ADP + P NADP Stroma Light reactions Calvin cycle Sugar used for Cellular respiration Cellulose Starch Other organic compounds 5/19/2021 44 Arunodoi Junior College
- 45. Check it! 1. Theprocess that uses the sun’s energy to make simple sugars is _____________. A. Cellular respiration B. Glycolysis C. Photosynthesis D. Photolysis 5/19/2021 45 Arunodoi Junior College PHOTOSYNTHSIS
- 46. Check it! 2. Thefunction accomplished by the light- dependent reactions is _______. A. Energy storage B. Sugar production C. Conversion of sugar D. None of these 5/19/2021 46 Arunodoi Junior College Energy Storage
- 47. Answer These…. 5/19/2021 ArunodoiJunior College 47 1. Which gas is needed for photosynthesis? 2. What type of energy is needed for photosynthesis? 3. Photosynthesis takes place in the membranes of small sacs called as ? 4. Colors of light most useful in photosynthesis are ? 5. What are the end products of Light reaction ? Carbon dioxide Light energy Thyllakoids Red & Blue ATP & NADPH
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