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Unformatted text preview: 503-441-611003-649-166303-564-580Life Sciences 2Section 2IBehn Khodayari23 April 2009Environmental and Evolutionary Affects on Pigment CompositionIntroductionPhotosynthesis is the primary source of direct and indirect energy for all living organisms on the planet. It is the chemical process by which sunlight energy is converted to chemical energy and is stored in the bonds of organic molecules. During this process, pigments absorb specific wavelengths of light and the resulting energy is used to fix carbon from carbon dioxide into glucose. These light-absorbing pigments include chlorophylls aand b, carotenoids, and phycobilins. The chlorophylls are the primary pigments while carotenoids and phycobilins function as accessory pigments that absorb different wavelengths of light and pass the energy along to the chlorophylls to be converted into use. In both experiments, we will be using two main techniques: thin layer chromatography (TLC) and spectrophotometry. TLC is a technique for separating organic compounds by dissolving the sample in a solvent and spotting it on a silica plate, while spectrophotometry allows measurement of the absorption spectrum of the extracted pigments. The first experiment examines the impact of growing barley in light or in the dark to determine environmental effects on pigment composition. Our hypothesis for this experiment states that dark-grown barley will have fewer pigments than light-grown barley. Our null hypothesis states that dark-grown barley will not have fewer pigments than light-grown barley. We believe that light-grown barley will have more pigments than dark-grown barley because in the light, the barley can perform photosynthesis and consequently will have chlorophylls visible. The second experiment compares the pigment composition of four photosynthesizers – red algae, green algae, brown algae, cyanobacteria – to see which ones share the most evolutionary history with barley. Materials and MethodsIn Experiment 1, we first collected 4-8 leaves of dark-grown barley and 2-4 leaves of light-grown barley. To prepare the barley for TLC, we grind the two types of barley in 3mL of methanol each using a mortar and pestle until the liquid becomes dark green (for the light-grown barley) and light yellow (for the dark-grown barley). We then pipetted the extract into a microcentrifuge tube, spinning the two in the centrifuge...
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- Fall '10
- Photosynthesis, Purple, Environmental and Evolutionary Affects on Pigment Composition