Plant Pigmentation and Photosynthesis Lab

4A Plant Pigment Chromatography

Purpose

The purpose of this experiment was to use Chromatography paper to identify plant pigments in spinach cells. We were testing to see if certain types of pigments were in spinach and the solubility of these pigments (Rf values). The relationship between the pigment and the solvent is the Rf value.

Introduction

The different pigments plants contain are carotene, xanthophyll, chlorophyll a and chlorophyll b. Paper Chromatography is used to separate the molecules because of the varying solubility of molecules in a certain solvent. It does this by separating the pigments using capillary action. This happens because solvent molecules are attracted to the paper as well as each other. When the solvent moves up the paper, it carries the pigments with it.  The distance the pigments travel is dependent on their solubility.  

Methods

In this lab we began by cutting a strip of chromatography paper into a pencil shape. (A long strip with a pointed end). Next, we scraped spinach cells off of a spinach leaf with a coin and dragged them across the chromatography paper, making sure that this green line did not go past the pointed end of the chromatography paper. We then hooked the chromatography paper onto a hook on the bottom of a stopper that was to go in a 50-ml graduated cylinder. The graduated cylinder had 1 cm of solvent in the bottom of it. We then made sure that the solvent only touched the pointed end and did not emerge the strip portion. The rest of the lab we let this chromatography paper sit and waited to record our results when the period ended, after the chromatography paper had diffused all of the spinach's pigments up the paper. 

Rubbing spinach cells onto chromatography paper

Placing the paper in into the test tube that holds the solution

Waiting..

Waiting...

Still waiting....

Measuring the distances traveled!

Measuring the distance of each band number 6.3-.6

Data

Graphs and Charts

Discussion

Our results contained the Rf values for 4 specific pigments found in spinach leaves: Carotene, Xanthophyll, Chlorophyll a, and Chlorophyll b. These results were directly related to how far each of them traveled up the chromatography paper. Each pigment was able to travel different distances up the paper because each pigment had different solubility levels and the chromatography paper is able to show this. A trend found in our data was the relationship between the distance of each pigment traveled and the Rf values of each of the same pigments. As a result if this, a conclusion can be made that the further the distance a pigment travels up the chromatography paper, the higher it's solubility is. The ones who traveled the furthest had the lowest Rf values and vice versa. These results were accurate and support our answer. If we were to change anything or re-do certain aspects of this lab we would have correctly measured the pigment's distances during the actual lab. Instead we just took pictures of the distances and referred to them because we were running out of tine by the end of this lab. Other than this, our lab was successful. Our results support this conclusion.

Conclusion

To conclude this experiment, spinach contained these 4 pigments: Carotene, Xanthophyll, Chlorophyll a, and Chlorophyll b. The solubility of these pigments were a directly related to how far the pigment traveled. Chlorophyll b had the lowest Rf value and traveled the shortest distance while Xanthophyll had the highest Rf value and traveled the furthest. Our data correctly supports this answer. 

References

http://www.gcisd-k12.org/cms/lib4/TX01000829/Centricity/Domain/783/2014%20Paper%20Chromatography%20of%20a%20Spinach%20Leaf%20Lab.pptx

4B Photosynthesis/ The Light Reaction

Purpose

The purpose of this experiment was to test whether light and chloroplasts are required in order for light reaction to occur.

Introduction

Many factors can either inhibit, help, or have no effect on Photosynthesis (light reactions). This lab was conducted to study this. DPIP, a compound posing as an electron acceptor, water, a phosphate buffer, and a spectrophotometer were used in this lab to reach the answer to this question. A dye-reduction technique is used in this experiment to study photosynthesis. 

Methods

To begin in this lab, we added the correct amount of DPIP, distilled H20, and phosphate buffer to each of the 5 cuvettes. The only one that did not contain DPIP was the first one. We made sure to wrap cuvette 2 in tin foil because no light was supposed to enter this cuvette. Each of the 5 cuvettes were measured in the spectrometer right after their mixtures were created. After each of these results were recorded, a 5, 10, and 15 minute time period was measured for each cuvette again. While one cuvette was in the spectrometer, the other 4 (except for number 2) were placed in front of a heat sink filled with water that was placed in front of a light.The heat sink's purpose was to absorb the heat so the cuvettes would experience no heat. After each of the 5, 10, and 15 minutes of the cuvettes were finished, we recorded our results.  

Measuring DPIP

Filling a cuvette with DPIP

Still filling

Exposing the cuvettes to light

All of the materials used

Unboiled chloroplasts 

Data

                                    % Transmittance

Graphs and Charts

Discussion

Unboiled/dark and Unboiled/light both had a significant increase in transmittance within the first five minutes of the experiment which shows that photosynthesis occurs in both light and dark environments while the chloroplasts are still alive. Contrarily, the chloroplasts that were boiled had very little growth as time went on which showed that the denatured chloroplasts hardly undergo photosynthesis.  The change in transmittance that was apparent with the boiled chloroplasts may be due to some of the sample not being fully denatured.  If this experiment were to be done again, it would be beneficial to make sure all of the chloroplasts are fully denatured so that there would be even less photosynthesis occurring within the boiled chloroplasts.  At the same time, it may be inevitable to have a portion of the sample could survive being boiled.  This comparison also shows that the light has much less of an impact on photosynthesis occurring than the nature of the chloroplasts, as those which were simply not exposed to the light still transformed, while the boiled chloroplasts were incapable of undergoing photosynthesis. The results we obtained are in sync with what we thought would happen because in order for plants to go through photosynthesis there needs to be a presence of light (in order to start the light/dark reactions) and chloroplasts, in order to absorb the light. If we conducted the experiment again, in order to see a more significant transmittance change, we would need to be more careful with how we mix or cuvettes as well as being more persistence with how much of each substance is being tested. Also, testing each cuvette between a certain time period rather than so close together so the time we collect our data is more exact, because that affects the transmittance measured.

Conclusion

To conclude this experiment, light does not have as big of an impact on photosynthesis as chloroplasts do. Our data generally supports this theory except for the slight differences in the transmittance levels of the boiled chloroplasts. In order for our data to completely support our theory, all of these levels should have been exactly the same. 

References

http://www.nature.com/scitable/content/the-light-and-dark-reactions-in-the-14705803

Cell Respiration Lab

Purpose

The purpose of this experiment was to observe the concentrations of carbon dioxide within a chamber during cellular respiration while various factors impacted in the process.  The independent variables were the temperature changes, and the germinating/non-germinating peas.  The dependent variables were the amounts of carbon dioxide produced and the rates of cellular respiration.

Introduction

Cellular respiration is the process cells undergo to break up sugars into a form that they can utilize as energy.  Cellular respiration takes in food and uses it to create ATP, a chemical the cell uses for energy. The process of cellular respiration consists of many different cycles, including the citric acid cycle.  During the citric acid cycle, carbon dioxide is produced and then later released as waste.

Methods

In this lab we tested the amount of oxygen consumption with the use of the devices. The beans, seeds, or glass beads were placed into the clear plastic container and we put the carbon dioxide and oxygen detectors into the openings on top of the container. The measures of these two gases appeared on the screen of the device. We then transferred this data onto each of our iPads.

Data 

The data from this lab explains the relationship between oxygen consumption and cellular respiration. 

Graphs and Charts

Discussion

It's evident that cellular respiration occurred in the peas. For the non germinated peas at room temperature, there was an increase in carbon dioxide while oxygen decreased. This means cellular respiration was at work and there was an exchange of the two gases. Similarly, for the non germinated peas with ice, there was an increase in carbon dioxide while the oxygen decreased. This shows non germinated peas were effected more then germinated peas. For the germinated peas in both room temperature and ice, there was little change in the oxygen and carbon dioxide levels. Germinated peas undergo cellular respiration because it's necessary for them to obtain energy this way. 

Conclusion

The germinating peas had the greatest celluar respiration of oxygen. The germinating peas had a faster process of cellular respiration than the non-germinating peas. The non-germinating peas required less energy, so because the dry peas were non-germinateing they had slower cellular respiration. The higher temperature caused the cellular respiration to occur faster and this caused a greater consumption of oxygen. The beads had no cellular respiration because they were unable to undergo the same process. 

 References

Enzyme Catalysis Lab

Purpose

The purpose of this experiment is to observe the change of hydrogen peroxide to water and oxygen gas by an enzyme catalase as well as to measure how much oxygen was made and calculate the rate of the enzyme-catalyzed reaction.

Introduction

Enzymes are proteins made from living cells that acts as a catalyst which affects the rate of a chemical reaction. In an enzyme-catalyzed reaction, the substrate binds  the active site of the enzyme. Each enzyme is specific for a certain reaction because each into acid sequence is unique and enzyme can be affected by the salt concentration, pH, temperature and activations and inhibitors.

Methods

We first created a base line in order to determine the hydrogen peroxide that is initially in the solution and use that base line to see the uncatalzyed rate of decomposition versus the catalyzed rate of decomposition. Sulfuric acid is added to inhibit the enzymes because of the acidic environment and cause it to stop reacting. After adding sulfuric acid, a 5-mL sample is taken in order to be titrated to see the catalyzed rate or change over time. potassium permanganate is added drop by drop from a burette until the solution is turned a pink or brown color.

Cups to be mixed fit various amounts of time.

When testing the baseline sample, there is initially a brown/pink color, but with some stirring, that hue disappears (pictures 1 & 2).  Once some potassium permanganate is in the solution and the color doesn't dissolve, the reaction has reached the end (picture 3).

Adding catalase extract (yeast) to begin reaction.

Adding Sulfuric Acid to stop reaction.

Taking a 5mL sample to test with potassium permanganate.

Test with potassium permanganate until there is a consistent pink or brown color.


Data

Discussion

The overall objective of the experiment was to observe the relationship between Hydrogen Peroxide and the catalase extract.  More specifically, observing the transformation of Hydrogen Peroxide to water and oxygen gas due to an enzyme catalase (in this case, the enzyme catalase was yeast).  Each time another aspect of the experiment was conducted, aka the catalase was left in the Hydrogen Peroxide for a longer period of time, the results varied.  From ten seconds to thirty seconds to sixty seconds, the amount of Potassium Permanganate consumed was sporadic, going from 3.2mL to 2.8mL, then back up to 3mL.  While these results were all very close, no true patterns were apparent.  In general, the amount of Potassium Permanganate consumed decreased between ten seconds and 360 seconds of the Hydrogen Peroxide solutions being mixed with the yeast.  The same applies to the amount of Hydrogen Peroxide used throughout the reaction: there was a general trend of decreasing of the usage of the solution as the length of time increased--although there were multiple instances in which the data did not follow the trend exactly.  For example, from ten seconds to thirty seconds to sixty seconds, the amount of Hydrogen Peroxide used initially decreased, but then increased right after.  The interval of time from 0-10 seconds had the highest rate because that is when there were the most enzymes and substrates present.  It is clear that the interval of 180-360 seconds had the lowest rate, which is because by the time the solution had been being mixed for so long, most of the enzymes and substrates were essentially used up, causing the reaction to plateau.  Since there was a relatively sure and consistent amount of the Hydrogen Peroxide, enzyme catalase, and Sulfuric Acid being used in each sample, and each time a titration took place, it was always with 5mL of the entire solution, the inconsistencies most likely come from the titration part of the experiment.  It is very easy to let a little too much Potassium Permanganate through the titration at once.  If too much is released when the pink or brown color was already sticking around, the results could easily be impacted.  To improve this experiment in the future, it would be important to make sure all measurements are accurate--from the amount of each solution used, to the amount of time each solution is mixed for.

Conclusion

Through this lab we observe how the catalase increases rate of decomposing of hydrogen peroxide. We see how hydrogen peroxide and enzyme catalase are able to work together. With the different time trials we are able to see how the enzyme breaks down hydrogen peroxide over a period of time. Uncatalzyed decomposition is slower than catalyzed decomposition of hydrogen peroxide. The catabolic process helps to speed up decomposition and break down, an example of our liver's ability to break down toxins.

Diffusion and Osmosis Lab

1A - Diffusion

Purpose

The purpose of the lab was to evaluate the diffusion of both large and small molecules through a semipermiable membrane.  We were testing to see if glucose would diffuse through the dialysis tubing.  The independent variable was 

Introduction

Diffusion is the random movement of molecules from a higher concentration to a lower one.  Osmosis is a specific type of diffusion, which involves water.  The movement of ions and molecules is not completely due to diffusion and osmosis, but also because of active transport.  Active transport moves a substance from a lower concentration to a higher one.

Methods

By taking dialysis tubing, which is semipermeable, filled with a glucose and starch mixture, we looked to see which substances would pass through the tubing from the water and iodine mixture it was submerged in.

Dark purple liquid within dialysis tubing, sitting in iodine solution. (After reaction)

Indicators for the presence of glucose throughout experiment.

Data

Discussion

Our results from this lab helped to further prove the laws of diffusion, osmosis, and the ability of membrane pore sizes to allow molecules to either pass or not pass through. From our data we can conclude that molecules in areas of high concentration will always move (diffuse) to areas of low concentration unless the molecules are too large to pass through the membrane or the membrane pores are too small. We know this to be true due to the fact that the contents inside the dialysis tubing and in the beaker had changed color by the end of the lab. Before the lab had begun, the beaker solution was a red/orange color and the dialysis tubing solution was clear. At the end of the experiment, the beaker was still a red/orange color but thr dialysis tubing solution had turned a purple color. This change in color was a result of the diffusion of iodine into the tubing. Iodine entered the tubing and glucose left the tubing. If we were to change or improve anything about this lab we would want specific amounts of solution (water, glucose, starch, etc.) so we could know how much to add to get even more accurate results. To conclude, our results were seemingly accurate and met the criteria of the laws of diffusion.

Conclusion

We found that glucose travelled from inside the cell to the solution. This means, in respect to the glucose, this was a hypertonic solution. Overall, this indicates iodine and starch cannot pass through the membrane as easily as glucose can.  The dark purple a appearance of the bag's contents indicates a change in the solution and solute. 

References

http://www.uic.edu/classes/bios/bios100/lecturesf04am/lect09.htm

1B - Osmosis

Purpose

Determine the water potential within a potato cell (plant cell), the different molar concentrations of sucrose that the potato cores are placed into determine this.  The independent variable is the molar concentrations of sucrose and the dependent variable are the potato cores. The change in sucrose helps to see the change in water potential. 

Introduction

Water always moves from area of high water potential to an area of low water potiential, meaning that water moves from an area with a lot of water to an area with little to no water. the water potential itself is affected by solute and pressure being added to or taken away from an area.  

Methods

Data

Discussion 

Our results from this lab helped to prove the laws of osmosis, the diffusion of water. Just like diffusion, osmosis strives for equilibrium. When a solution is hypotonic this means that it has a low level solution and a high level of water. When a solution is hypertonic this means that is has a high level of solution and a low level water. In order to reach equilibrium, more water is required in hypertonic solutions and less water is needed in hypotonic solutions. Water always diffuses from an area of high concentration to an area of low concentration. This is proved in our lab because after soaking different solutions of sucrose in dialysis tubing that was submerged in water, the masses of the tubing changed. Osmosis had occurred. If we were to repeat this lab and improve it, we would have measured the solutions more precisely in order to get more uniform answers and would have also been more careful when drying and weighing the solutions in the dialysis tubing. The results of our lab further prove the laws of osmosis. 

Conclusion

References

1C - Water Potential 

Purpose

Introduction

Methods

Coring the potatoes.

Data

Discussion

Our results from this lab helped us determine the water potential of each potato cell and what water potential really is. Our data proves that areas of high water potential will always move to areas of low water potential. Water potential is affected by two things; pressure potential and solute potential. Our data also proved that water potential and solute potential are inversely related. If solute potential is high then water potential will be low and vice versa. Our data is seemingly accurate due to the fact the fact that these points were proven. If we were to improve any aspects of this lab we would Improve the measurements. Not all potato cells/solutions/etc. we're exactly the same. This means that not all data corresponded to each other. This means that the results were a bit more difficult to compare and contrast. Overall, this experiment went well and got accurate and favorable results. 

1E

Disscusion

Plasmolysis is movement of water out of the plant cell and shrinking of the of the plant cell due to the loss. The water that is diffused out of the cell goes into a hypertonic solutionthat is surrounding the cell.  The space between the cytoplasm and the cell wall is filled with the exertonic solution. Because an oninon cell is a plant cell and the area around the onion has a lower water potential so the  water would move out of the cell. If plant cells are exposed to a hypertonic solution such as salt water, the water in the plant cell is drained  from the cell and into the hypertonic salt water around it.

Refrence

http://biologymadesimple.com/topics/absorption-by-roots/absorption-by-roots-page-4/

Milk Lab

Purpose 

In this lab, we were trying to determine the actual percentage of protein on skim milk. We were testing protein properties (such as protein denaturation). In this scenario, the dependent variable would be the molecular structure and the the independent variable would be the acetic acid added to the milk.

Introduction 

Proteins are macro-molecules composed of chains of amino acids. The sequences of amino acids usually result in the different structures (primary, secondary, tertiary and quaternary) which then determines it's function. When a chain of amino acids come together, they form polypeptide bonds.  

Methods 

In this lab, we started off by weighing an empty beaker so we could later subtract this mass from the mass of the liquid and the beaker combined. We then measured out 15-mL of non-fat milk into the beaker. Next we added acetic acid to the beaker filled with milk and stirred it. We then recorded the mass do the solution and the beaker together. Next we poured the solution through a filter paper and into a beaker. The filter paper caught the curds. We then let the filter paper and curds dry out over night and massed it the next day. 

Data

Discussion

The overall objective of the experiment was to determine the percentage of protein that is in nonfat milk, according to the label there is supposedly 8 grams of protein per serving. We calculated a -31.152% error meaning that we had approximately 30% less protein found in our milk then our expected value. The reasons behind this error could be as follows: incorrect measurements and the filter paper used to filter out the protein. In order to revise and improve the experiment for another test, there must be a more efficient way for filtering the milk solution and separating out the proteins. More precise measurements and calculations would help to determine a more accurate account for the protein. 

The results of the experiment support our hypothesis on the outcome of the experiment because protein was shown to be present when the milk and its proteins were in the process of separating. When Biuret reagent was added, the remaining coagulated milk turns a purple color meaning that protein leaked through the funnel into the liquid and separated from the rest of the protein. 

. 

(Amount of Protein Per Serving: 8g)

Sample from Non-fat milk

Adding concentrated acetic acid to milk

Acid denatures milk protein

Milk begins to form curds

Solution poured into funnel to separate protein

Using water as negative control.

Adding Biuret to milk solution.

Purple color shows presence of protein in solution. 

Separating protein from funnel.

Setting filter paper to dry overnight.

Conclusion 

To conclude our experiment, the actual percentage of protein found in skim milk (due to our findings) was much less than what we expected it to be. The carton said there was supposedly 8 grams. We found a lot less than this. We are basing our information off of the data we found in this lab. There might have been skewed data from incorrect measurements at times but generally our findings were accurate.

References

http://en.m.wikipedia.org/wiki/Whey

http://chemistry.about.com/od/foodscienceprojects/a/Yogurt-Chemistry.htm