Chap 10 PPT - CHAPTER 10 Photosynthesis Photosynthesis is...

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Unformatted text preview: CHAPTER 10 Photosynthesis Photosynthesis is the process that converts solar energy into chemical energy Directly or indirectly, photosynthesis nourishes almost the entire living world Autotrophs sustain themselves without eating anything derived from other organisms Autotrophs are the producers of the biosphere, producing organic molecules from CO 2 and other inorganic molecules Almost all plants are photo autotrophs How can sunlight, seen here as a spectrum of colors in a rainbow, power the synthesis of organic substances? These organisms feed not only themselves but also most of the living world Heterotrophs obtain their organic material from other organisms Heterotrophs are the consumers of the biosphere Almost all heterotrophs, including humans, depend on photoautotrophs for food and O 2 BioFlix: Photosynthesis BioFlix: Photosynthesis (a) Plants (c) Unicellular protist 10 m 1.5 m 40 m (d) Cyanobacteria (e) Purple sulfur bacteria (b) Multicellular alga Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes Chloroplasts: The Sites of Photosynthesis in Plants Leaves are the major locations of photosynthesis Their green color is from chlorophyll , the green pigment within chloroplasts Light energy absorbed by chlorophyll drives the synthesis of organic molecules in the chloroplast CO 2 enters and O 2 exits the leaf through microscopic pores called stomata Chloroplasts are found mainly in cells of the mesophyll , the interior tissue of the leaf A typical mesophyll cell has 3040 chloroplasts The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast); thylakoids may be stacked in columns called grana Chloroplasts also contain stroma , a dense fluid Leaf cross section Vein Mesophyll Stomata CO 2 O 2 Chloroplast Mesophyll cell Outer membrane Intermembrane space 5 m Inner membrane Thylakoid space Thylakoid Granum Stroma 1 m Photosynthesis Photosynthesis can be summarized as the following equation: Chloroplasts split H 2 O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules Photosynthesis is a redox process in which H 2 O is oxidized and C O 2 is reduced 6 CO 2 + 12 H 2 O + Light energy C 6 H 12 O 6 + 6 O 2 + 6 H 2 O Reactants: 6 CO Products: 12 H O 6 O 6 H O C H O The Two Stages of Photosynthesis: A Preview Photosynthesis consists of the light reactions (the photo part) and Calvin cycle (the synthesis part) The light reactions (in the thylakoids): Split H 2 O Release O 2 Reduce NADP + to NADPH Generate ATP from ADP by photophosphorylation The Calvin cycle (in the stroma) forms sugar from CO 2 , using ATP and NADPH The Calvin cycle begins with carbon fixation , incorporating CO 2 into organic molecules Light H 2 O Chloroplast Light Reactions NADP + P ADP i + ATP NADPH O 2 Calvin Cycle CO 2 [CH 2 O] (sugar) The Nature of Sunlight Light is a form of electromagnetic energy, also...
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This note was uploaded on 09/14/2011 for the course BIOL 2301 taught by Professor Staff during the Spring '11 term at Lone Star College System.

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Chap 10 PPT - CHAPTER 10 Photosynthesis Photosynthesis is...

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