Bio%20201%20S12%20Lect%2013%20%28True%29%20v3

excrete salt to outside and excreted

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Unformatted text preview: http://upload.wikimedia.org/wikipedia/ commons/thumb/9/98/Euphorbiavirosa.jpg/200px-Euphorbia-virosa.jpg http://www.ceoe.udel.edu/halophyte/ Halophyte%20Agri.htm THE BASICS OF PHOTOSYNTHESIS •  Almost all plants are photosyntheEc autotrophs, as are some bacteria and proEsts –  Autotrophs generate their own organic maNer through photosynthesis –  Sunlight energy is transformed to energy stored in the form of chemical bonds (c) Euglena (b) Kelp (a) Mosses, ferns, and flowering plants (d) Cyanobacteria Light Energy Harvested by Plants & Other PhotosyntheEc Autotrophs 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2 Even the most efficient photosynthesis in nature is able to capture only 5% of the energy in sunlight EvoluEonary pressures have pushed plants to this efficiency level, and pushed some groups of plants to be able to perform photosynthesis in stressful environments (dry, hot) Photosynthesis occurs in chloroplasts •  In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts •  A chloroplast contains: –  stroma, a fluid –  grana, stacks of thylakoids •  The thylakoids contain chlorophyll –  Chlorophyll is the green pigment that captures light for photosynthesis •  The locaEon and structure of chloroplasts Chloroplast LEAF CROSS SECTION MESOPHYLL CELL LEAF Mesophyll Intermembrane space CHLOROPLAST Outer membrane Granum Grana Stroma Inner membrane Stroma Thylakoid Thylakoid compartment Steps of Photosynthesis THE LIGHT REACTION •  Photons hit reacEon centers of chlorophyll, found in chloroplasts •  Chlorophyll vibrates and causes water to break apart •  Oxygen is released into air, Hydrogen remains in chloroplast aNached to NADPH THE “DARK” REACTIONS = Calvin Cycle CO2 from atmosphere is joined to H from water molecules (NADPH) to form glucose AN OVERVIEW OF THE PROCESS •  The light reacEons convert solar energy to chemical energy Light Chloroplast –  Produce ATP & NADPH •  The Calvin cycle makes sugar from carbon dioxide –  ATP generated by the light reacEons provides the energy for sugar synthesis –  The NADPH produced by the light reacEons provides the electrons for the reducEon of carbon dioxide to glucose NADP+ ADP + P Light reacJons Calvin cycle HypotheEcally ancestral photosynthesis light reacEon •  Process for ATP...
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This note was uploaded on 10/02/2013 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

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