Solutions For Macromolecules As An Unknown Solution Essay

1203 Words Oct 4th, 2016 5 Pages
The purpose of this lab is to test different solutions for macromolecules as well as to identify an unknown solution. This experiment used three tests to identify which macromolecules (carbohydrates and proteins) were present in different sample solutions. The tests were the iodine test, Benedict’s test, and the biuret test.
To begin, the iodine test was used to identify which solutions contained glycogen or starch. If the solution tested negative, it stayed the yellow colour of the iodine solution. Whereas, if the solution tested positive for glycogen it turned a red-brown colour (Morris, 1946). Additionally, the solution turned a blue-black colour if the iodine reacts starch (Bailey & Whelan, 1961). For this test, the positive controls were the 1% glycogen and the 1% starch solutions. This is due to the fact that this test was testing specifically for those macromolecules. The negative control was the distilled water because it does not have impurities that would react with the iodine solution (or any other solution test) to cause it to be positive.
Another test that was done was the Benedict’s test. This experiment tests for reducing sugars. Reducing sugars are sugars that are oxidised and lose electrons (Simoni, Hill, & Vaughan, 2002). For this test, a solution that produced a yellow to red precipitate indicates it is positive. In contrast, if the solution is negative it will remain a clear blue solution or have a dark brown precipitate…

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