3 Remember what it means to be a plant… Need to produce all organic molecules necessary for growthcarbohydrates, lipidsproteins, nucleic acidsNeed to store chemical energyin stable formcan be moved around plantsaved for a rainy day
4 + water + energy glucose + oxygen AutotrophsMaking energy & organic molecules from light energyphotosynthesis+ water + energy glucose + oxygencarbondioxide6CO26H2OC6H12O66O2lightenergy+So, in effect, photosynthesis is respiration run backwards powered by light.
5 build stuff !! Light reactions Convert solar energy to chemical energyATPNADPH energy reducing power build stuff !!
6 CO2 contains little energy because it is fully oxidized How is that helpful?Want to make C6H12O6synthesisHow? From what? What raw materials are available?CO2CO2 contains little energy because it is fully oxidizedReduce CO2 in a series of steps to synthesize a stable energy storage moleculeNADPHreduce CO2carbon fixationNADPC6H12O6
7 From CO2 C6H12O6 CO2 has very little chemical energy fully oxidizedC6H12O6 contains a lot of chemical energyreducedendergonicReduction of CO2 C6H12O6 proceeds in many small uphill stepseach catalyzed by specific enzymeusing energy stored in ATP & NADPH
8 From Light reactions to Calvin cycle chloroplast stromaNeed products of light reactions to drive synthesis reactionsATPNADPH
13 Summary of photosynthesis 6CO26H2OC6H12O66O2lightenergy+Where did the CO2 come from?Where did the CO2 go?Where did the H2O come from?Where did the H2O go?Where did the energy come from?What’s the energy used for?What will the C6H12O6 be used for?Where did the O2 come from?Where will the O2 go?What else is involved that is not listed in this equation?
14 Supporting a biosphere On global scale, photosynthesis is the most important process for the continuation of life on Eartheach year photosynthesis synthesizes 160 billion tons of carbohydrateheterotrophs are dependent on plants as food source for fuel & raw materials
15 The poetic perspective All the solid material of every plant was built out of thin airAll the solid material of every animal was built from plant materialsunairThen all the cats, dogs, mice, people & elephants… are really strands of air woven together by sunlight!