Photosynthesis (Chromatography) (Lab 4)

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Thylakoid Membrane
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Located in the chloroplasts; where the light (\”photo\”) reactions take place
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Stroma
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Fluid inside a chloroplast; where the light independent/calvin cycle occurs (\”synthesis\”)
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Photoreceptors
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Trap light energy Many photoreceptors are pigments
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Chlorophylls
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Greenish pigments that occur in all photosynthetic plant tissues and capture light for photosynthesis. Different molecular groups lead to different wavelengths of light absorbed. They also vary in solubility in water and polarity.
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Chlorophyll a
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Essential photosynthetic pigment. Blue-green pigment. Occurs in all photosynthetic eukaryotes and cyanobacteria (such as Oscillatoria and Gloeocapsa).
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Chlorophyll b
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Accessory pigment that captures additional light energy and transfers it to chlorophyll a
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Chlorophyll c
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Pigment found in certain types of algae
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Carotenoids
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Yellow, orange, and red pigments. Act as accessory pigments. Also add color to plants and fruit to enhance pollination and fruit dispersal. Two groups: carotenes and xanthophylls
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Accessory Pigments
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Pigments that capture additional light and transfer it to chlorophyll a
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B-Carotene
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Yellow-orange carotene. Essential dietary supplement in animals. Used to form vitamin A.
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Xanthophylls
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Yellow pigments. These pigments are so similar that they cannot be separated from each other using the paper chromatography technique
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Paper Chromatography
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Method used to analyze pigments. Pigment-containing mixture is put on a strip of paper, which is then put into a solvent. The pigments get separated from each other according to polarity. Polar molecules: stick/adsorb to the charged, polar chromatography paper and remain at the base of the paper Nopolar molecules: travel with the solvent (which is nonpolar) and go up the paper
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Adsorb
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To adhere to the surface of another compound without forming a chemical bond
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Reference Front (Rf value)
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distance substance travels from origin (where the pigment is) ————————(over)————————————————- distance solvent travels from origin
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Chromatogram
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A complete array of colored bands (in order from origin to solvent front: chlorophyll b, chlorophyll a, two xanthophylls, and beta-carotene)
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The Hill Reaction
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Photosynthesis can occur without carbon dioxide, as long as there is a source of light and an electron acceptor. Led to the confirmation that water was the source of electrons AND oxygen in the \”photo\”/\”light\” reactions of photosynthesis. Showed that the light and dark reactions can be separated from each other. Showed that the electron transport chain converts light energy into chemical energy
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Photosynthesis
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Chemical reaction that converts non usable carbon dioxide into usable carbon in the form of glucose (light energy from the sun into chemical energy). Consists of 2 phases: light reactions and \”dark\” or \”light independent\” reactions. 6H2O + 6CO2 + light –> C6H12O6+6O2
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Light Dependent/\”Photo\” Reactions
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Occur in the thylakoid membranes. Solar energy excites electrons found in water, water molecules get split (hydrolysis), and NADP+ is reduced (gains electrons), becoming NADPH. Also results in the creation of ATP
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Light Independent/\”Synthesis\” Reactions (Calvin Cycle)
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Occurs in the stroma of a chloroplast. ATP, NADPH, and CO2 are converted into carbohydrates/sugars (specifically glucose).
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Reduced
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RIG: R________ is gained (obtains electrons)
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Oxidized
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OIL: O________ is lost (loses electrons)
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DPIP
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A blue dye that acts as an electron acceptor. In the photosynthesis experiment, used as a substitute for NADP+. Goes through a series of redox (reduction-oxidation) reactions. Changes color from blue to colorless when it has been reduced (electrons have been added), indicating that photosynthesis has occurred

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