Introduction to Photosynthesis
       Introduction to Photosynthesis
     •  Life is solar powered. 
     •  photosynthesis captures light energy from the sun and 
        converts into chemical energy that is stored in sugars 
        and other organic molecules, ATP..
     •  Photosynthesis nourishes almost all of the living world 
        directly or indirectly. Some Bacteria do not need it. 
     •  Photosynthesis has 3 stages. 1. Energy is captured 
        from the sun light. 2. Light energy is converted into 
        chemical energy which is stored as ATP and NADPH. 
        3. The energy stored in ATP and NADPH powers the 
        formation of organic compounds using CO2.
                                       
                                       
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     Cont……….
    • Autotrophs are the producers of the biosphere 
       they get their energy from in organic sources like 
       light. 
    • There are photoautotrophs and 
       chemoautotrophs.
    • Heterotrophs live on organic compounds 
       produced by other organisms, autotrophs. 
       Consumers.
        –Almost all heterotrophs are entirely relianton 
          photoautotrophs for food and for oxygen
    • So the circle of life starts with photosynthesis.
                                        
                                        
      Where Does Photosynthesis Occur
      Where Does Photosynthesis Occur
     •  Occurs in the chloroplasts of plant or photosynthetic 
        organism cells. 
     •  Any green part of a plant contains chloroplasts
     •  But, leaves are the major site of photosynthesis for most 
        plants.
         – There are about 500,000 chloroplasts per square 
           millimeter of leaf surface. 
     •  color of a leaf comes from chlorophyll, the green 
        pigment in the chloroplasts. It reflects green wavelengths 
        of light. 
     •  Chloroplasts are found mainly in mesophyll, the middle 
        tissue of a leaf.
                                        
                                        
    Cont……….
    Cont……….
 • O  exits and CO  enters the leaf via tiny pores, 
     2              2
   stomata, in the leaf.
 • Veins carry water from the roots and carry off 
   sugar from mesophyll cells to other plant areas
                                 
                                 
 Chloroplast Structure
 Chloroplast Structure