Photosynthesis


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Chloroplast is found in all the green parts of a plant. However, the leaves are the major source of photosynthesis for most plants. The color of the leaf comes from chlorophyll, which is the green color in the chloroplasts. Chloroplasts are mainly found in mesophyll cells that form the tissues in the inner of the leaf. Veins deliver water from the roots and carry off sugar from mesophyll cells to non-photosynthetic. The typical or normal, mesophyll cell has thirty to forty chloroplasts and each of them is about two to four micros by four to seven microns long. The equation describing the process of photosynthesis is: 6CO2 + 12H2O + light energy ? C6H12O6 + 6O2+ 6H2O. C6H12O6 is glucose. One of the first clues to the device/mechanism of photosynthesis came from the discovery that the O2 given off by plants comes from H2O, not CO2. The customary hypothesis was that photosynthesis spilt carbon dioxide and then added water to the carbon. Step One is CO2 ? C + O2. Step two is H2O ? CH2O. The hydrogen that is extracted from the water is incorporated into sugar and oxygen is released to the atmosphere, where it can be used in respiration.

Photosynthesis is a redox reaction. It reverses the direction flow in respiratation. Water is split and elections are transferred with H+ from water to CO2, reducing it to sugar. Because the electrons increase in potential energy as they move from water to sugar, the process requires energy. Light provides the energy boost. Photosynthesis is two processes and each has multiple stages. The Light (photo) reactions convert solar energy to chemical energy. The Calvin Cycle (synthesis) uses energy from the light reactions to incorporate CO2 from the atmosphere into sugar. In the light reactions, light energy absorbed by chlorophyll in the thylakoids drives the transfer of electrons and hydrogen from water to NADP+, forming NADPH. The light reaction also generates ATP using chemiosmosis into a process called photophosphorylation. Therefore, The light energy is initially transformed to chemical energy in the form of two compounds, which are NADPH, and ATP. The Calvin Cycle is names for Melvin Calvin. With his colleagues, Calvin worked out many of its steps in the 1940s. The cycle begins with the incorporation of CO2 into organic molecules, a process known as carbon fixation. The fixed carbon is reduced with electron which are provided by NADPH.

Sources:
-Biology 8th edition textbook, Solomon Berg Martin
-www.course-notes.org
-Mt. Sinai library database
-http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/LightReactions.html
-www.tamu.edu/classes/bich/bmiles/lectures/photosystems.pdf
-http://www.britannica.com/eb/article-60574/photosynthesis


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