Macromolecules Lab Experiment
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, …show more content…
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 (Daniels, Rush, & Bauer, 1960). In addition, the positive control was the 1% glucose solution. Once again, the negative control that was used was distilled water for the same reasons expressed …show more content…
Next, the 1% glucose, 1% maltose, and 1% lactose solutions turned red-brown as well as had a precipitate form. The honey solution turned brown and also had a precipitate form. The protein solution turned a dark blue colour and the beer solution turned yellow.
Table 3: Biuret Test Results
Beaker Contents Colour
1% Glucose solution Light clear blue
0.3% Glucose-1-phosphate solution Light clear blue
1% Maltose solution Light clear blue
Honey solution Yellow / green
1% Sucrose solution Light clear blue
1% Lactose solution Light clear blue
1% Glycogen solution Light clear blue
1% Starch solution Light clear blue