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Biology 20 Unit 3 Chapter 5 Photosynthesis

Biology 20 Unit 3 Chapter 5 Photosynthesis

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Biology 20 Unit 3 Chapter 5 Photosynthesis

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  1. Biology 20 Unit 3Chapter 5 Photosynthesis McGraw - Hill Ryerson pages 169 to 181

  2. Photosynthesis A process that converts solar energy into chemical energy Mean ‘Light” and “to make or build”. Occurs in all plants, some algae, some bacteria, some protists light 6H2O + 6CO2 ----------> C6H12O6+ 6O2

  3. Light Part of electromagnetic radiation (EMR) Can be described by its wave characteristic or as particles of energy called photons. Chloroplasts and Photosynthetic Pigments

  4. A spectroscope separates individual wavelengths of the Sun • Visible light is only 3 % of the total energy

  5. I.) Chlorophyll Light – absorbing, green colored pigment Absorbs photons and begins process of photosynthesis Color of pigment comes from wavelengths of light reflected (in other words, those not absorbed). What color is absorbed if you see a red shirt? What colors are reflected?

  6. Types of Chlorophyll All photosynthetic organisms have chlorophyll "a"  Accessory pigments absorb energy that chlorophyll "a" does not absorb Pigments include: Chlorophyll "b" (also c, d, and e in algae and protistans) Xanthophylls Carotenoids

  7. Absorption spectrum of chlorophylls “a” and “b”

  8. Spectrophotometer Instrument that determines wavelengths of light absorbed or reflected by a pigment Chlorophyll "a" reflects green light waves and absorbs red and blue

  9. Leaves during fall season Onset of cooler autumn temperatures and less sunlight Plants stop producing chlorophyll molecules Reveals yellow, red, brown colors of leaves. leaves Pumpkin Eyes Games

  10. II.) Chloroplasts Found in leaves Primary photosynthetic organs of most plants Structure of the leaf Chloroplasts have chlorophyll Captures light for food production Xylem and phloem transport water and food Gases enter and exit from stomata Waxy cuticle and epidermis protect plant from water loss

  11. Xylem Structure Phloem Structure

  12. LeafAnatomy

  13. Chloroplast anatomy 1. 2 membranes Outer and inner 2. Stroma Protein – rich semi liquid material in interior of chloroplast Between two membranes

  14. 3. Thylakoid System of interconnected flattened membrane sacs Form a separate compartment within stroma of chloroplast Stack on top of one another, forming grana 1 chloroplast has 60 grana Each has 30 – 50 thylakoids

  15. 4. Lamellae Groups of unstacked thylakoids Between grana

  16. 5. Thylakoid membrane and lumen Photosynthetic membrane within chloroplast Contains: Light – gathering pigment molecules Electron transport chains Lumen: Fluid – filled space inside a thylakoid

  17. Chloroplast

  18. Chloroplast structure Structure of thylakoid system greatly  surface area of thylakoid membrane Thus,  efficiency of photosynthesis Chloroplasts are able to replicate, through division, independently of cell Lipid droplets and starch grains are also present in chloroplast Plant growth

  19. Separating Pigments Using Chromatography • Paper chromatography is a method used to separate different compounds in a solution • As solvent moves up paper, it will carry dissolved compounds of solution • Compounds move up paper at different rates due to their solubility in the solvent and their size

  20. tip of the filter paper is placed in solvent • as solvent moves up the paper it will carry pigments size:smaller pigments travel further up paper solubility:more soluble pigments travel further up paper

  21. The Reactions of Photosynthesis A process made up of a series of complex chemical reactions. A variety of intermediate and final energy rich molecules are formed. Occurs in the thylakoid membrane and stroma of the chloroplast. light 6H2O + 6CO2 ----------> C6H12O6+ 6O2 Photosynthesis

  22. Energy is stored when ATP is formed • Energy is released, when needed, by reversal of reaction ATP Energy input Energy output ADP + Pi

  23. Oxidation – Reduction Reactions • Oxidation • A reaction in which an atom or molecule loses electrons • Reduction • A reaction in which an atom or molecule gains electrons • Electron transfers between 2 substances always involve both oxidation / reduction reactions • “LEO” the lion says “GER”

  24. Oxidation / reduction examples i.) ATP Reduction of ADP ADP (accepts electrons) + Pi ATP Storage of energy Oxidation of ATP (energy) ATP (releases elections)  ADP + Pi Release of energy ADP and Pi can be reused in future reduction reactions

  25. ii.) NADPH Reduction of NADP+ NADP+ + H  NADPH NADPH is now stable and can release energy to the next electron acceptor Oxidation of NADPH NADPH  NADP+ + H NADP+ can be reused in future reduction reactions Oxidation / reduction examples

  26. I.) An Overview of Photosynthesis 3 stages 1. Capture solar E and transfer it to e- 2. Use captured solar energy to make ATP; transfer high energy e- to NADP+; NADPH is then used as a high energy e- carrier 3. Use energy stored in ATP and NADPH to form energy – rich molecules such as glucose, from CO2

  27. Photosynthesis *Reworked equation: 12 H2O + 6 CO2 + solar E → C6H12O6 + 6 O2 + 6 H2O light 6H2O + 6CO2 ----------> C6H12O6+ 6O2

  28. * Reactants of photosynthesis are the products of cellular respiration. Photosynthesis

  29. Light Dependant (Stages 1 and 2) A.k.a.noncyclic photophosphorylation or noncyclic electron flow I.e., linear and ADP + Pi Require chlorophyll Occur in thylakoid membranes of chloroplast

  30. Light Independent (Stage 3) occur during day or night AKA: Calvin cycle Carbon fixation occurs Incorporation of CO2(g) into organic compounds such as glucose Occur in stroma of chloroplast Use ATP and NADPH from light dependent reactions Enzymes are required

  31. . W

  32. Stage 1: Capturing Solar Energy Photosystems- in thylakoid membranes Cluster of chlorophyll and other pigments packed into thylakoid membranes. Photosystem I uses chlorophyll "a", in the form referred to as P700 Photosystem II uses a form of chlorophyll "a" known as P680 Operate so that a wide range of wavelengths can be used for photosynthesis. Why?

  33. Action of a photosystem

  34. All pigments within a photosystem capture and absorb photons. Only 1 pair of chlorophyll molecules/photosystem actually use solar Energy Found at core of reaction center of photosystem Antenna pigments Other pigment molecules Gather light and transfer it to chlorophyll molecules Stage 1: Capturing Solar Energy

  35. Solar E is captured when a low energy e- in a chlorophyll molecule, from photosystem II, absorbs a photon. Energy is channeled to chlorophyll a. After a photon of light strikes, chlorophyll a molecules absorb solar E. Donates the electron to the primary electron acceptor in the thylakoid membrane. Because chlorophyll a donates an electron, it must get another one from somewhere… the splitting of water! Stage 1: Capturing Solar Energy

  36. Twoenergized e-, from chlorophyll, are removed from photosystem II e- enters an electron transport chain e- is passed from one molecular complex to another (like a hot potato) ATP is made because of the energy release through the chain. Series of oxidation / reduction reactions Stage 1: Capturing Solar Energy

  37. Photolysis Occurs in thylakoid lumen Solar E absorbed by chlorophyll is used to split water into H+, e-, O2(g) e- replaces 2e- lost by chlorophyll molecules in photosystem II O2(g) exists plant through stomata in leaves or is used to make H2O H+ will be used later, to help reduce ADP Stage 1b- Photolysis

  38. 2 H2O (l) + energy  4 H+ + 4 e- + O2(g) Stage 1: Capturing Solar Energy