Abstract. Photosynthesis is the process that plants use to harness the energy of the sun through light and use it to create sugars. Photophosphorylation is the first step of photosynthesis and occurs in the chloroplast. Light is captured by light harvesting complexes. The light excites electrons which excite surronding electrons through resonance induction and excite special pairs of electrons. These electrons help pump protons into the chloroplast lumen creating a proton gradient. Photosystem I also absorbs light and excites electrons which are used to pump more protons. ATPsynthase facilitates the mvement of the protons back down the proton gradient allowing for the phosphorylation of ADP to ATP. In C3 plants, carbon reduction follows. This cycle breaks uses the enzyme RubisCO to create two 3 carbon sugars which can then be converted into more sugars to be used by the plant. In our experiment, we watch the rate of photophosphorylation, or the Hill Reaction, by using DCIP dye, which is blue when oxidized and colorless when reduced, and measuring the absorbance of a chloroplast suspension with a spectrometer. We can see how inhibitors alter the usual photosynthetic cycle and how plants evolve adaptations to deal with trying climatic conditions.
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Introduction
PHOTOSYNTHESIS IS ARGUABLY THE MOST IMPORTANT REACTION to living things. It is the initial reaction that harnesses light and converts it to sugars which are filtered up the food chain. Since this reation is so important, it is looked at in great detail many different times. In these experiments, we look at the effect that inhibitors have on the rate of the Hill Reation. Photophosphorylation is the first process of photosynthesis and its rate is very important to the process as a whole. We also look at how leaf structure can help a plant survive in their environment. C3 plants
Cited: Calkins, Erin. 2013a. The Hill Reaction. Lab in Cell Biology lab: 2 April 2013. Santa Barbara: Santa Barbara City College. ___________. 2013b. Leaf Microstructure. Lab in Cell Biology lab: 2 April 2013. Santa Barbara: Santa Barbara City College. Friesen, Larry Jon. 2013. Photosynthesis. Cellular Biology Website: 21 April 2013. Santa Barbara: Santa Barbara City College. Hoyt, Richard. Adaptations of the Yucca Plant. eHow. Wynia, R.L. 2010. Plant fact sheet for New Jersey tea (Ceanothus americanus). Manhattan: USDA-Natural Resources Conservation Service.