Macromolecules 210 PDF

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Lab report for professor rami alsaber on macromolecules...

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Anissa Zibo Laboratory Report: Testing for the Presence of Macromolecules Introduction: The 4 major macromolecules present in living organisms are proteins, carbohydrates , lipids and nucleic acids. These are called macromolecules because they are built of small unit called monomers. Monomers are linked together through a process called dehydration synthesis. Carbohydrates are chains of carbons, hydrogens and oxygens in a 1:2:1 ratio. They usually Lipids are generally fats and contain phospholipid bilayers and are formed through hydrophilic heads and hydrophobic tails. These layers are formed tail to tail. Nucleic acids are the building blocks of DNA and RNA and are composed of chains of nucleotides. Hypothesis: Carbohydrate: If simple sugars have a pH of 8 or higher the benedict's reagent will react and cause a solid precipitate. The higher in pH the sugar is the precipitate will show in either green, yellow, orange or reddish brown. If sugars have lower pH levels we will use the Barfoed tests will show a change in color as well. The iodine in the iodine test will react with polysaccharides and turn black-blue in color. Lipids: If the substance is a lipid then the sudan IV dye will dissolve and the stain on the brown paper bag in the grease spot test will be translucent. Proteins: If a peptide bond is present it will give a violet color, while free amino acids will not react. Materials: For carbohydrates we used Benedict’s reagent, Barfoed reagent, Lugol’s iodine, 1% sucrose, glucose, fructose, lactose, starch, water, potato juice, onion juice, karo syrup, white bread, apple, test tubes, hot plates, tongs, test tube holders, test tube rack, marking pencil, stirring rods, spot dish, wax pencil or marker, disposable pipettes, 10 mL graduated cylinder, 600 mL beaker.

For testing the presence of lipids we used Sudan IV powder, water, oil, white brad, unknown lipid solution 1, disposable test tubes, test tube racks, wax pencil or marker, brown paper towel, 1 mL pipettes, 5 mL pipettes and a pipette dispenser. For proteins we used a biuret reagent, water, dilute gelatin, histidine, trypsin, test tubes, racks, stirring rods, wax pencil, 1mL pipettes, 5 mL pipettes, pipette dispenser Experiment/ Procedures: The testing for the presence of carbohydrates was the use of the benedict's test. The procedure was to set up a boiling water bath for each of our labeled test tubes to be boiled for 5 minutes once the solution was put into place. For Barfoed's test we did the same thing but before we boiled each substance e added the barfoed reagent and boiled this down for two minutes. Finally ina depression dish we had a drop of each solution and added a couple of drops of iodine to said solutions, looking for color changes. The testing of lipids was used with the Sudan IV test. We added 1 mL of oil and a few drops of sudan IV, we also did the same with water and we had one test tube that had both substances. Ultimately we ended up testing things such as white bread and an unknown substance. The sudan IV dissolved in oily substances which we assumed to be lipids. The unknown substance was assumed to be a lipid as well because it turned red. The next procedure we did was a very simple task. To determine whether something was a lipid or not, we put one drop of it on a brown paper bag and took note of its color. If the paper bag became transparent then it was a lipid, if it wasn't transparent and was dark in color it was another liquid. When testing proteins we did the Biuret test. This test we had 6 test tubes. Test tube 1 had water and the biuret reagent, test tube 2 had egg albumen and the biuret reagent, test tube 3 had the histidine and reagent, test tube 4 had trypsin and the reagent, test tube 5 had the gelatin solution and the reagent and

finally the last test tube had a unknown protein solution and the reagent. Finally we allowed for this to stand for 5 minutes. Results:

As expected, carbohydrates that were found in Barfoed, Benedicts and the Iodine test all showed similar results. The only carbohydrates that were present were the potato juice, white bread and starch. These all were a greenish to blue color and turned black when mixed with iodine. These substances also did not produce a precipitate. With lipids, the Sudan IV test showed that even when mixed with water, lipids will float to the top of water and the sudan IV will still dissolve in only the oil. Anything that was not a lipid produced an opaque color in the sudan IV test and did not produce a transparent spot in the grease spot test. Finally with proteins, the Biuret test showed those that were proteins produces a purple to violet color when left alone with the reagent, everything else that was not a protein remained light blue.

Discussion/conclusion: Within these scientific observation,we discovered the properties of what it means to be considered a lipid, protein and carbohydrate. These tests proved to be useful in many way. On determining a solutions solubility as well as determining whether a solution can be considered hydrophobic or hydrophilic was useful as well. In conclusion, carbohydrates seem to have a reaction when having a ph of 8 or higher just as we hypothesized when it came to the benedict's test. Lipids were easily detected when it came to the grease spot test because this is a reality that we all live and we see it very frequently. The sudan IV test also was really useful especially when it only dissolved in the lipid solution that was sitting on top of the water. The Biuret test was useful in identifying starched and how they react with the agent, it was also very useful to notice that no matter the form all starches that were present in this experiment reacted the same way.

References: Aryal, S., J., M., Y., A., J., . . . N. (2018, June 11). Benedict's Test- Principle, Composition, Preparation, Procedure and Result Interpretation. Retrieved from https://microbiologyinfo.com/benedicts-test-principle-composition-preparation-procedure-and-result-int erpretation/ Luckie, D. (n.d.). Lab 1. Retrieved from https://msu.edu/course/lbs/145/luckie/Lab1.html...