Chapter 10- Photosynthesis

Chapter 10- Photosynthesis - 1/31/2010 Photosynthesis 2010:...

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1/31/2010 1 Photosynthesis © 2010: D. Julian Photosynthesis feeds the biosphere Photosynthesis is the process that converts solar energy into chemical energy. Directly or indirectly, photosynthesis nourishes almost the entire living world. © 2010: D. Julian Autotrophs and heterotrophs 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, using the f li ht t k i ll f energy of sunlight to make organic molecules from H 2 O and CO 2 . 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 . © 2010: D. Julian
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1/31/2010 2 (a) Plants Photosynthesizers Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes. (c) Unicel ular protist 10 μm 1.5 μm 40 μm (d) Cyanobacteria (e) Purple sulfur bacteria (b) Multicel ular alga © 2010: D. Julian Chloroplasts The green color of plants is from chlorophyll , a green pigment. Chlorophyll is contained within chloroplasts . Light energy is absorbed Stomata CO2 O2 Mesophyl Vein Leaf cross section by chlorophyll, which drives the synthesis of organic molecules in the chloroplast. Therefore, chloroplasts are the sites of photosynthesis in plants. © 2010: D. Julian 5 μm Mesophyl cel Chloroplast Locations of photosynthesis The parts of plants that can contain chloroplasts include leaves, stems and unripe fruit, but leaves are the major locations of photosynthesis. Chloroplasts are found Stomata CO2 O2 Mesophyl Vein Leaf cross section mainly in cells of the mesophyll, the interior tissue of the leaf. A typical mesophyll cell has 30–40 chloroplasts. © 2010: D. Julian 5 μm Mesophyl cel Chloroplast
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1/31/2010 3 Stomata CO 2 enters the leaf and O 2 exits the leaf through microscopic pores called stomata . Stomata CO2 O2 Mesophyl Vein Leaf cross section © 2010: D. Julian 5 μm Mesophyl cel Chloroplast Chloroplast structure The chlorophyll is in the membranes of thylakoids (connected sacs in the chloroplast). Thylakoids may be stacked in columns called grana Chloroplast Intermembrane Outer membrane Thylakoid . Chloroplasts also contain stroma , a dense fluid. © 2010: D. Julian 1 μm Thylakoid space Granum space Inner membrane Stroma The photosynthesis equation Photosynthesis can be summarized as the following equation: 6 CO 2 + 12 H 2 O + Light energy C 6 H 12 O 6 + 6 O 2 + 6 H 2 O Simplifying: CO + H O [CH O] + O © 2010: D. Julian CO 2 + H 2 O [CH 2 O] + O 2 Photosynthesis is a redox process in which H 2 O is oxidized and CO 2 is reduced.
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1/31/2010 4 Following the atoms Reactants: 6 CO 2 Products: 12 H 2 O 6 O 2 6 H 2 O C 6 H 12 O 6 © 2010: D. Julian Chloroplasts split H 2 O into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules.
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This note was uploaded on 01/31/2011 for the course BSC 2010 taught by Professor Bowes during the Spring '08 term at University of Florida.

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Chapter 10- Photosynthesis - 1/31/2010 Photosynthesis 2010:...

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