Photosynthesis

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Photosynthesis is one of the most important processes in this universe. Plants are known as autotrophs, meaning that they make their own food (Urry et al. 155). They make their own food by going through the process of photosynthesis. If photosynthesis does not occur, then the plants will not survive. Heterotrophs, organisms that do not make their own food, need plants for food in order to provide energy for the organelles in their cells (Urry et al. 155). Without photosynthesis, autotrophs will not survive, and without plants, heterotrophs will not survive. In order for photosynthesis to make food, the plant must go through a complicated process to provide the energy it needs to drive the functions of its organelles.
The complete equation for photosynthesis is:
6CO2 + 12H2O + Light Energy C6H12O6 + 6CO2 + 6H2O (Urry et al. 157). Carbon dioxide gains electrons and is reduced to glucose.
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It is called the dark reactions because light is not required directly for this step to occur. It is called the Calvin cycle because Melvin Calvin and his colleagues, in the 1940’s, discovered the steps of the Calvin Cycle (Urry et al. 159). The Calvin Cycle occurs in the stroma of the chloroplast (Anderson). The first phase of the Calvin Cycle is carbon fixation. CO2 (reactant in photosynthesis) is absorbed into the chloroplast. The CO2 binds with a five carbon sugar by rubisco. Then this new six carbon compound breaks into two three-carbon compounds (Urry et al. 168). The second phase is reduction. ATP and NADPH are used for energy, becoming ATP and a phosphate group and NADP+, and a sugar called G3P is made. This sugar is then transformed into glucose (product of photosynthesis). The third phase is regeneration of the CO2 acceptor. Three ATP are used to drive the synthesis of rubisco (Urry et al. 168). Now the Calvin Cycle can start over again. The Calvin Cycle uses nine ATP and six NADPH (Urry et al.

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