Photosynthesis

=PHOTOSYNTHESIS:=

Website: http://apbiologyportals.wikispaces.com/Photosynthesis http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html http://biology.clc.uc.edu/Courses/bio104/photosyn.htm http://biologyeoc.wikispaces.com/Photosynthesis http://biologyeoc.wikispaces.com/CellOrganelles http://onlinebiotext.wikispaces.com/Photosynthesis

Photosynthesis is an anabolic process that utilizes light energy to synthesize carbohydrates. Organelles known as chloroplasts play an important role in photosynthesis. These organelles contain chlorophyll, which is the major pigment of photosynthesis. Chlorophyll contains a porphyrin ring that absorbs light energy. There are many types of chlorophyll, and the most vital pigment is chlorophyll a, while chlorophyll b is an accessory pigment. There are the light dependent reactions, in which ATP and NADPH are formed. Chlorophyll captures light energy, which allows a single electron to move to a higher energy level. This propels energy of these electrons to phosphorylate ADP to form ATP. This also forms NADPH. The source of electrons for electron transport chain during noncylic electron transport is H20. ATP production is instigated by photophosphorylation. The light independent reactions are seen in the Carbon fixation reactions. This process basically needs carbon dioxide to make carbohydrates.

In order to facilitate carbon fixation in hot, and dry environments, plants use C4 pathway. This process is able to fix carbon dioxide at low concentrations, by utilizing PEP carboxylase, an enzyme that speeds up the reaction by which CO2 reacts with phosphoenolpyruvate (PEP), which forms oxaloacetate. This captures carbon dioxide and is able to provide it to the bundle sheath cells extremely efficiently. The CAM pathway fixes carbon dioxide at night, during very dry conditions. CAM plants open the stomata at night, and store malate in cell vacuoles. The stomata are closed during the day, which reduces water loss. An example of a CAM plant would be the Prickly pear cactus (Opuntia). Photosynthesis is very important to plants, and many other organisms in sustaining life. This process replenishes oxygen for the use of all aerobic organisms, and is necessary in life. Photosynthesis is comprised of many complex processes, which are intertwined to aid in sustaining the life of many organisms that rely on it. Photosynthesis plays an important role in biology, and supporting life.

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