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ETD 36: A. Draw and Explain how the chromatography experiment works + why it is useful? B. Draw + Explain the Basic steps of the light and dark rxns of photosysnthesis.
December 19, 2013 at 8:05am


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Kevin Turek
January 01, 2014 at 1:28pm

Parent: Kevin told me that chromatography paper tells you how similar the substances are too the solvent. He said that this is a way to measure the Rf distance. Then he said that the light are in the thylakoids of the chloroplast. This absorbs the light and co2. It also uses NADP+ and ADP+P. This goes through photosystems 1 and 2. This will produce O2 and also produce ATP and NADPH (which acts as an electron carrier. These 2 products go into the Calvin cycle (Dark rxns). This will produce NADP+ and ADP+P.

Student: This was one of the harder ones to explain to my mother. She didn't really understand the chromatography paper. But this was probably because I  was a little confused on it too and could not explain it well enough. But other than this she seemed to understand the light systems and dark rxns. It was similar to explaining cellular respiration. This also may have been because I had studied this a little more then I did chromatography paper. 

Sophie Wulfing
January 14, 2014 at 8:34pm

Parent  A:  Crush up a leaf, put it on Chromo. paper, and put it in water to soak up the water.  The paper is polarized so the pigments that are most polarized soak up further.  The "RF" value is the distance of pigment / distance of the entire solvent 

B:  light reactions are where light hits chlorophyll on the leaf, light energy goes into the thylakoids of the leaf.  Photo-system 2 then 1.  Produces ATP which goes to the dark reactions, from there the Calvin (and Hobbes) cycle uses CO2 & the ATP to create G3PO (half of a glucose molecule)  Recycles ADP & NADP+ (e- carrier) back into the light reactions.  

Sophie- The polarity of each substance is relative to the other solvents that move up the paper. As for the light/dark reactions, I had to review the basic inputs and outputs, for example that light reactions take in light energy (blue or red) and produce the 02. The dark reactions take in CO2 and produces G3P. The two recycle NADP+ and ADP back and forth to eachother, the light reactions supplying the extra p and elections to make it ATP and NADPH.

Madison Boggan
December 09, 2014 at 5:24pm

Parent: Leaves can be rubbed in a line onto paper using a coin or something similar in order to transfer the pigment onto the paper. This can also be done with proteins, DNA, RNA. When the tip of the paper is put into solvent, the solvent travels up the paper taking the pigment (or whatever) with it and leaving it in bands. The distance traveled depends on the solvent and the polarity of the pigment. The point is to separate the parts of the pigment in this case and it can then be studied from there once isolated.

DPIP acts as an electron acceptor when the thylakoid membrane within a chloroplast is damaged.

Student: The chromatography experiment reminds me of gel electro because of the way that the parts travel in bands based off of their make up. I realized this connection as I explained it to my mom. I wonder all the types of information that can be gathered through experimenting with chromatography.

Also, I wonder how someone first discovered what DPIP does.

Talesh Patel
December 14, 2014 at 9:27pm

Parent:  A) Talesh explained with his drawing that Chromatography is used to determine polarity of plant matter by measuring how far pigments travel using a solvent.  Generally, Beta Carotene travels the furthest and is most polar and most soluble.   B) in light reactions, light energy and 2 H2O's combine in the chloroplast's thyllakoid to form O2, ATP, and NADH . The NADH and ATP combine with CO2 to produce G3P which is half of a glucose molecule and produces NADP, which is a phosphate not a hydrogen molecule.

Student: A. I drew a picture of a graduated cylinder that contained chromotography paper and solvent to show my mom how phytopigments travel up the paper from the area where plant matter is rubbed. The further the pigment travels, the more soluble and polar it is because it bonds better with the solvent and "hitchhikes" up the paper. Beta carotene travels the furthest, and has a yellow-orange color to it. Xanthophyll is a little less soluble and has a yellow color. Chlorophyll A has a bright green color and is the 2nd least soluble. The least polar is chlorophyll B and is yellow green to olive green. The distance these phytopigments travel can be used to find the Rf value. Taking the distance of the pigments and dividing it by the total distance of the solvent yields this value.B. Light energy accepted into the chloroplasts is paired with 2 H2O to create O2, ATP, and NADH. The ATP and NADH are used in dark reactions with CO2 to produce G3P, half of a glucose. The NADP+ and ADP are recycled to supply and extra phosphate and extra electrons making ATP and NADPH. When you take G3P and have 1000x of them, they create Cellulose which is the structure of plants (think wood.. and ultimately paper).

Lauren Masters
January 02, 2016 at 6:07pm

Parent: Lauren showed me the diagram of the chromatography paper and the spread of the pigments. She explained how the polarity and solubility affects the distance the color travels on the paper.  Different colors have different travel distances. She talked about determining the rf value.

Student: I showed my mom the drawing in my ETD. I explained that the phytopigments were separated by polarity. Beta carotene traveled the farthest because it is non-polar and the most soluble. Chlorophyll B travels the shortest distance because it is most polar and least soluble. Each pigment has a different color so that they can be determined when looking at the chromatography paper. I also taught my mom how to calculate rf values. rf = distance pigment traveled divided by distance of solvent.

Soleia Weisenburger
January 03, 2016 at 6:26pm

Parent: Soleia explained to me that using chromatography paper can be used to determine the phytopigments this was done by rubbing a leaf using a coin to transfer the pigment to the paper and put in a solvent to determine the polarity of the phytopigments. Light and Dark reactions in the chloroplast when the light photons hit the chloroplast and the light reactions use the NADP which are resident in the stroma to enter the PS1 and PS2 which release 02 for people to breath. The dark reactions pull in the CO2 from the air and release 1/2 a glucose but because it goes through twice produces a whole glucose to be used by energy for the cell.

Student: This was harder to explain because my dad was struggling to understand NADP it helped me to understand because at first I was struggling to understand it myself I also showed in my science journal to show how everything looks so that he could have a visual to go along with what I was trying to say. For the most part he understood the chromatography lab but was not sure of what phytopigments are. 

Katarina Zosel
December 14, 2017 at 11:05pm

Older Sister: Part A: The chromatography experiment helps and is useful because it separates the pigments. Carrots are super positive so they go far. Part Bee: the light reaction in the thylakoid leads to the release of NADPH to the dark reaction called Clavin cycle which releases 3 part Carbons that are mashed together in the stoma to create glucose. 

Student: I first drew a picture of the chromatography paper with the lines of photopigments and explained how the bonds and varying levels of polarity created the separation. It was helpful when I outlined each individual step of the light and dark reactions. I drew out the Chloroplast and the ps2 and ps1 cells then explained how it was very similar to the chemiosmosis in plants as the cell builds up a proton gradient that goes through an ATP synthase. For the dark reaction, I drew out the new Calvin cycle emphasizing how rubisco is the most abundant protein on earth and how important RuBp was. Then for a bonus, I explained what happens in photorespiration when there is not enough co2 and how harmful it is to plants.

Hitesh Boinpally
December 30, 2017 at 10:04pm

Parent: A) I learned from Hitesh about chromatography experiment. It was interesting to learn about how chromatography paper is able to separate phytopigments based on their polarity and beta carotene is a very non-polar substance and travels the furthest.

B) He talked about light reaction and dark reaction. Light reaction involves light and uses photo system 1 and 2. It emits oxygen. Dark reaction takes place through calvin cycle using rubisco and CO2, creating G3P which can be stored as starch eventually. I found it interesting how the ADP + Pi and NADP+ are recycled between the two cycle. 

Student: It was hard for me to explain the chromatography experiment because I didn't completely understand it. However, after doing extra research and looking back over my notes I understood it better and how polarity plays a part in the whole experiment and allows the different solutes to spread the way they do. The light and dark reactions were fairly easy to explain in a basic sense, but I had to look up what rubisco did (used to catalyze the first step of carbon fixation) just to refresh my memory. Overall, explaining the questions to my parents helped clarify a lot of how the chromatography experiment worked and the light/dark reactions of photosynthesis.

Sarah Kropelnicki
January 27, 2019 at 9:05pm

Parent: This ETD was especially confusing to me, but Sarah did a good time trying to explain it. Chromotography is a way to seperate pigments by their charge. The darker pigments stay closer to the tip while the lighter ones travel up the paper. 

Student: I remember not really understanding the spectrophotometry or chromotopraphy lab super well so I wasn't able to teach this as effectively as others. I will need to read up on what these concepts really mean. 

Zach Holtz
December 09, 2019 at 10:25pm

Student:   It was a nice review to explain to my mom how chromatography works and why it is useful.  I started by telling her that chromatography is the separating of pigments by polarity.  When looking at the lines on the paper used in our experiment, the upper most line represents the solvent front which is non-polar due to it having no charge.  As you go down from line to line, each pigment starts to get more and more of a negative charge.  The reason why those are lower is by it being attracted to the paper which is polar and it causes it to move slower.  After that I went to go explain the basics of light and dark rxns.  It starts out with light energy and H2O entering the chloroplast.  After that, they enter the thylakoid which they participate in PS 1 and 2.  The products of these are ATP and NADPH.  Those then go to the dark rxn which is the calvin cycle and take in CO2 and produce G3P and NADP+ and ADP+Pi which can be used again to repeat and continue the whole cycle.

Parent:   I love experiments.  I had a blast relearning the separation of pigments during chromatography.  Having the spinach released in the solvent and then watching the separations occur up the testing paper is cool to watch.  The colors light and dark green at the bottom, closest to the solvent shows stronger charges.  Then it separates out the yellow then orange, with orange having the lower charge. The basic steps of light and dark reactions is a bit complicated.  The light reactions (ATP and NADPH products) deal with photosystems I & II and the dark reactions (ADP + Pi and NADP+) deal with the Calvin cycle.  When H2O and CO2 come into the chloroplast O2 and sugar are produced.  This is a cyclic process.

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