The main thing was always keeping those fractions in

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in P2 conical tubes. The main thing was always keeping those fractions in an ice container. The pellets and supernatant are only out of ice when moving to the centrifuge. Next, move on part II: we determined which fraction has the most chloroplast by using photosystem. We used DCIP, a chemical function like NADP+ but also changed color under reactions, to monitor what is happening. In this experiment, 12 cuvettes were needed. In general, the cuvettes contained Chloroplast Isolation Buffer, water, DCIP, and cell fraction. Four of them, which didn’t contain DCIP, were blanks. These cuvettes were not the controls. We used them for calibration, to adjust the set. Another four cuvettes had all chemicals and in an optimum condition for photosynthesis happens. These 8 cuvettes were placed in the illumination apparatus. The fours left also had everything in but stayed in the dark condition. We wanted to test photosynthesis with no light. These were negative controls in our experiment. One cuvette from each category above didn’t have cell fraction; they were another negative control in this experiment. We picked other 3 cuvettes, one of each category, and put P1 in; we did the same for P2 and S2. We ran the experiment by using spectrophotometer for each tube in 3 times, with 8 minute intervals. The key thing here was we didn’t put any cell fractions into the cuvettes until we were ready for that reading. The reactions occurred immediately at the moment cell fractions were put into the solution. The experiment was performed at room temperature, under normal pH, and with a light source. From the graph 1, we see that all fraction absorbances tended to decrease consistently over the time, except for L1 and D1. You may not see L1 because D1 is overlapping it. L3 dropped a huge amount compared to others. Based on graph 2, we know L3 had the largest changing, 94%; next was L4 and L2. D2, D3, and D4 had slightly changing in absorbances, around 4.4 to 7.1%. These “dark cuvettes” are our negative controls.Part IIIOur group tested for the activity chloroplast electron chain under the changing levels of pH. Because the intention was to see how chloroplast electron chain functions when pH is exposed to environmental changes, we used the cell fraction that had the most chloroplasts from previous work, P2, for this experiment. There were total 6 cuvettes: a blank, a positive control, a negative control, and three more cuvettes with different pH range from light acidic to light basic. Because we were testing how pH affects chloroplast electron chain functions, we kept all other conditions the same (light, temperature, and amount of cell fractions). The experiment was run in 3 minute intervals and 3 times for each tube.

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