Sunday, January 12, 2014

Photosynthesis Lab

Purpose(lab 1): to use chromatography to separate the photosynthetic pigments found in spinach

Introduction(lab 1): chromatography is a technique for separating materials. Some pigment is smeared near the bottom of the chromatography paper and when the bottom is dipped in a solution, it travels up the paper, taking the pigments with it. Over time the pigments end up spread out along the paper because they traveled up with the solution.

Methods(lab 1):for this lab we smeared spinach at the bottom of the chromatography paper and then dipped the bottom of that chromatography paper solvent. This caused the pigments in the spinach to travel up the paper with the solvent. We then measured to see what pigment was most plentiful in the spinach.
Data(lab 1):

Graphs and charts(lab 1):

Discussion(lab 1):
Paper chromatography separates pigments by dissolving them in a solvent that moves up a strip of paper by capillary action. Different pigments travel different distances up the paper because of their varying solubility and attraction to the paper. For example, beta carotene is more soluble and less attracted to the paper and will be carried further than less soluble, more attractive pigments like xanthophyll. The distance traveled by the pigments is called Rf. Each pigment has its own Rf. It can be calculated by dividing the distance the pigment moved by the distant the solvent front moved. The orange pigment that went the farthest is called Carotene. The green that went the least is called chlorophyll b. this means that carotene is the most soluble and that chlorophyll b is the least.

Conclusion(lab 1): orange traveled the farthest at 11 cm and green traveled the least at 1.7 cm. that means that the most plentiful pigment was carotene and the least plentiful was chlorophyll b. our results are fairly accurate. The only way the data would be wrong is if we read the measurements wrong on the ruler.

References(lab 1): the lab

Purpose(lab 2):the purpose was to see the effects of light changes and boiling the chloroplasts on photosynthesis using DPIP. The independent variable was whether or not the chloroplasts were boiled and the amount of time it spent in the light. The dependent variable was the percent transmittance. The control was the group with no DPIP and the group with no chloroplasts.
Introduction(lab 2): photosynthesis is the process that turns light into sugar. The first half requires light to work. The light energy is absorbed by the chlorophyll which initiates the reactions. When the light is diminished or taken away, the process slows down. After the light is absorbed it goes into the chloroplast. If the chloroplasts are boiled, the proteins would be denatured, and thus wouldn't work.

Methods(lab 2):In this lab we used a colorimeter to see the photosynthetic pigments and how they were different between each other after 5, 10, and fifteen minutes. We used DPIP to activate the reaction and we went to see the breaking down of pigmentation in the spinach. We used a beaker of water to block the heat coming from the flood light, and to keep the dark chloroplasts in the dark we used aluminum foil to cover the tube to avoid contact with light to see how that would affect the reaction.

Data(lab 2):

Graphs and charts(lab 2):

Discussion(lab 2):
All of our data seems wrong for this lab. We think what we were using the colorimeter wrong. It's also possible that our timing was wrong.
for this lab the first cuvette had no DPIP which was the replacement electron carrier. This made it the control. DPIP replaces NADP+ which when reduced completes the light reactions for photosynthesis. This cuvette should've had the lowest percent transmittance because of the lack of DPIP, but me must've screwed up as this cuvette has the highest in our results. The second cuvette had unboiled chloroplasts in the dark. The absence of light makes it so electrons can't travel through photosystem II. this should've caused a lower %transmittance, but our data didn't support this. We think that's because of the reasons at the beginning of the discussion. Cuvette 3 had unboiled chloroplasts in the light. This means that the chloroplasts could go through photosynthesis normally. There was nothing hindering it. The photons from the light would carry the electrons all the way through the process. Cuvette 4 had boiled chloroplasts in the light. The act of boiling them denatured them. That means that they can't go through the act of photosynthesis. Essentially, the chloroplasts were broken. This should've caused a really low percent transmittance like the first cuvette, but like the first cuvette, out data doesn't support it. In the 5th cuvette, there were no chloroplasts. This would cause absolutely no photosynthesis.

Conclusion(lab 2): this lab had the highest absorption In run 2 (unboiled chloroplasts light) and the lowest in run 3 (boiled chloroplasts light). Our data actually shows the highest reading in the first minute of run 4 but this must be a mistake because that run had no chloroplasts in it. Run 3 was the lowest because the chloroplasts were boiled which rendered them useless. Run 2 worked the best because nothing was altered. Our results don't seem correct, though. It's possible that we took the readings wrong or we interpreted the data wrong.

References(lab 2): the lab

Purpose(lab 3): the purpose of this lab was to see if we could improve on lab 2 by making the absorption higher and by making the percent transmittance lower.

Introduction(lab 3): this lab is the same as lab 2 except we used half the dpip (an electron carrier that replaces NADP+)

Methods(lab 3):We used the same procedure, and methods as part 2 but changed one area,we chose to change the amount of dpip going into the procedure. We ended up speeding up the reaction, when in fact we wanted to take away dpip, leading us to slow down the reaction. 

Data(lab 3):

Graphs and charts(lab 3):

Discussion(lab 3):we thought that halving the DPIP would improve our results in the experiment, but it was actually the opposite of what we wanted to do. We should've doubled the DPIP. with the extra DPIP, more electrons would've been able to make their way through, thus improving our results

Conclusion(lab 3): our modification to the experiment didn't work. We got more absorption with less percent transmittance. Except in run 2 where the absorption was higher at first, but was lower in the rest of the measurements than the original lab. This is because the DPIP was used up faster since there was less of it. 

References(lab 3): the lab