Experiment to Identify Macromolecules

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18th May 2020 Chemistry Reference this

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Identification of Some Macromolecules

Introduction

 

 The goal of this experiment is to react certain solutions using different tests, which consist of the Iodine test, used to determine the presence of starch and glycogen through colour change (Morris, 1946), Benedict’s test, used for determining the presence of sugars (Benedict, 1908), and the Biuret Test, used for determining the presence of proteins (Gornall, Bardawill & David, 1948), to identify certain macromolecules, a large, organic molecule, that exist within these solutions.

Materials and Methods

 All of the procedures were carried out as outlined in Lab 2: Identification of Some Macromolecules, BIOL 130L lab manual, pages 27- 30 (Department of Biology, 2019). The unknown solution used in beaker #12 in this experiment was solution #61.

Results                 Legend: (+) Positive Results after the test      (-) Negative Results after the test

                                                                      Iodine test                Benedict’s Test               Biuret Test  

                            Initial Colour                 yellowish tint                  blue tint                       blue tint

#1                    colourless/transparent          yellow (-)           light orange/red (+)            light blue (-)

                                                                   transparent                  opaque                       transparent

#2                    colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                    transparent                 transparent                   transparent

#3                    colourless/transparent           yellow (-)               orange/red (+)                light blue (-)

                                                                   transparent                   opaque                        transparent

#4              slight yellow tint/transparent     yellow (-)           brownish green (+)           light turqoise (-)

                                                                   transparent                   opaque                       transparent

#5                    colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                    transparent                 transparent                   transparent

#6                   colourless/transparent          yellow (-)                light orange (+)              light blue (-)

                                                                   transparent                  opaque                        transparent

#7                   colourless/transparent        brownish/red (+)            blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

#8                  colourless/transparent         black/blue (+)                blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

#9               murky white with bubbles       yellow (-)                     blue (-)                 lavender purple (+)

                           translucent                    transparent                    transparent                   transparent

#10              light yellowish-brown            yellow (-)                 mustard yellow (+)         light green (-)

                           tranparent                     transparent         precipitate formed, opaque     transparent

#11                colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                   transparent                 transparent                   transparent

#12                colourless/transparent         black/blue (+)                blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

Discussion

When referring to the results and the introduction, we can come to conclusions about the presence of specific macromolecules existing within certain tested solutions in this experiment. All of the data matched the expected values and results except for two tested solutions, #4, the 5% honey solution and #10, the beer, as there were unexpected colouration differences from the expected results with the honey solution and the beer but that was caused by the original base colour of the solution. Overall, there weren’t many errors within the techniques and data since most of the procedure is quite straightforward and didn’t demand anything too challenging, and if not the majority, all of the data collected is qualitative and approximate. Starch contents turn blue when reacted with iodine (Holló & Szejtli, 1957), and the only solution tested positive for starch was solution #8, the 1% starch solution. This being the only matching reaction with our unknown solution, we can conclude that the unknown solution in our test was a starch solution as well.

References

Identification of Some Macromolecules

Introduction

 

 The goal of this experiment is to react certain solutions using different tests, which consist of the Iodine test, used to determine the presence of starch and glycogen through colour change (Morris, 1946), Benedict’s test, used for determining the presence of sugars (Benedict, 1908), and the Biuret Test, used for determining the presence of proteins (Gornall, Bardawill & David, 1948), to identify certain macromolecules, a large, organic molecule, that exist within these solutions.

Materials and Methods

 All of the procedures were carried out as outlined in Lab 2: Identification of Some Macromolecules, BIOL 130L lab manual, pages 27- 30 (Department of Biology, 2019). The unknown solution used in beaker #12 in this experiment was solution #61.

Results                 Legend: (+) Positive Results after the test      (-) Negative Results after the test

                                                                      Iodine test                Benedict’s Test               Biuret Test  

                            Initial Colour                 yellowish tint                  blue tint                       blue tint

#1                    colourless/transparent          yellow (-)           light orange/red (+)            light blue (-)

                                                                   transparent                  opaque                       transparent

#2                    colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                    transparent                 transparent                   transparent

#3                    colourless/transparent           yellow (-)               orange/red (+)                light blue (-)

                                                                   transparent                   opaque                        transparent

#4              slight yellow tint/transparent     yellow (-)           brownish green (+)           light turqoise (-)

                                                                   transparent                   opaque                       transparent

#5                    colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                    transparent                 transparent                   transparent

#6                   colourless/transparent          yellow (-)                light orange (+)              light blue (-)

                                                                   transparent                  opaque                        transparent

#7                   colourless/transparent        brownish/red (+)            blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

#8                  colourless/transparent         black/blue (+)                blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

#9               murky white with bubbles       yellow (-)                     blue (-)                 lavender purple (+)

                           translucent                    transparent                    transparent                   transparent

#10              light yellowish-brown            yellow (-)                 mustard yellow (+)         light green (-)

                           tranparent                     transparent         precipitate formed, opaque     transparent

#11                colourless/transparent           yellow (-)                     blue (-)                     light blue (-)

                                                                   transparent                 transparent                   transparent

#12                colourless/transparent         black/blue (+)                blue (-)                      light blue (-)

                                                                   opaque                       transparent                   transparent

Discussion

When referring to the results and the introduction, we can come to conclusions about the presence of specific macromolecules existing within certain tested solutions in this experiment. All of the data matched the expected values and results except for two tested solutions, #4, the 5% honey solution and #10, the beer, as there were unexpected colouration differences from the expected results with the honey solution and the beer but that was caused by the original base colour of the solution. Overall, there weren’t many errors within the techniques and data since most of the procedure is quite straightforward and didn’t demand anything too challenging, and if not the majority, all of the data collected is qualitative and approximate. Starch contents turn blue when reacted with iodine (Holló & Szejtli, 1957), and the only solution tested positive for starch was solution #8, the 1% starch solution. This being the only matching reaction with our unknown solution, we can conclude that the unknown solution in our test was a starch solution as well.

References

  • Benedict, S. R. (1908). A REAGENT FOR THE DETECTION OF REDUCING SUGARS. Sheffield Laboratory of  Physiological Chemistry, Yale University
  • Department of Biology. (2019). Introductory cell biology laboratory. Waterloo, Canada: University of Waterloo Print + Retail Solutions
  • Gornall, A. G., Bardawill, C. J., & David, M. M. (1948). DETERMINATION OF SERUM PROTEINS BY MEANS OF THE BIURET REACTION. Department of Pathological Chemistry, University of Toronto, Toronto, Canada
  • Holló, J., & Szejtli J. (1957) THE MECHANISM OF STARCH-IODINE REACTION.  Institute of Agricultural Chemical Technology, University of Technical Sciences, Budapest.
  • Morris, D. L. (1946). COLORIMETRIC DETERMINATION OF GLYCOGEN DISADVANTAGES OF THE IODINE METHOD.  Department of Nutritional Research, Mead Johnson and Company, Evansville, Indiana

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