Cellular Respiration Lab Report

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Register to read the introduction… We then set the wavelength to 600nm, the wavelength at which DPIP absorbs light. We then used the control knob to set the spectrophotometer by turning the transmittance level to 0%, with the cover closed and the chamber empty. After labeling four different cuvettes B, 1, 2, 3 corresponding to each trial, we prepared the blank (B) solution. Using a micropipette, we measured 4.6 ml buffer, 0.3 ml mitochondrial suspension, and 0.1 ml succinate into the B cuvette that contained no DPIP. Before placing the cuvette in the spectrophotometer, we wiped down the sides and aligned the mark on the cuvette with the line on the holder to ensure that the reading came from the clear side of the cuvette. After closing the cover, we adjusted the light control so that there was a 0% absorbance with our control in the machine. This ensured that our experimental samples were only showing readings for the light absorbed by the DPIP and not by the mitochondrial suspension as well. Tube 1 consisted of 4.4 ml buffer, 0.3 ml DPIP, 0.3 ml mitochondrial suspension, and 0 ml of succinate. This served as a control because there was no succinate to give off electrons and reduce the DPIP. Tube 2 consisted of 4.3 ml buffer, 0.3 ml DPIP, , 0.3 ml mitochondrial suspension and 0.1 ml succinate. This was the trial with a low …show more content…
My prediction was also supported because raising the succinate concentration did indeed lead to the transmittance raising. While the experiment was effective in producing the results that I expected, errors were made and there was room for improvement. One possible source of error is differing times in between adding the succinate and measuring the transmittance between trials. Ideally, we would’ve placed the completed solution in the spectrophotometer immediately after introducing the succinate. However, this was not possible and the times between adding the succinate and taking the first reading differed among trials. The effect of this is simply that some reactions will have started before others, and some may be farther along when the first and subsequent readings are taken. Another possible source of error is insufficient mixing of the tubes before transmittance readings. Not mixing the tubes properly may allow some of the important elements of the substance to settle at the bottom, giving the tube an inaccurate reading. Improvements on the experiment include more trials for each tube. An increase in trials would enhance the reliability and credibility of the data. Another possible improvement would be to include more succinate concentrations. While, this would require more work, having more tubes with higher concentrations of

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