Four Major Biological Macromolecules

Introduction The objective of this experiment is to identify if the 12 provided solutions contain starch, glycogen, reducing sugars or proteins. The four major biological macromolecules are carbohydrates, lipids, proteins and nucleic acids. Abundant elements in the world such as carbon and nitrogen bond in different ways to form many different molecules. The functional groups are what determine their characteristics. During the experiment, there will be 3 test. The iodine test is completed to test for starch and glycogen. When iodine is mixed with a solution that contains starch, the amylose will react, turning the solution blue/black. If iodine is mixed with a solution containing glycogen, it will
Firstly, a source of error may occur during the Benedict 's test. Positive results may occur when their should not be. This is due to the fact that there may be a presence of another substance that can be oxidized other than reducing sugars. Furthermore, another source of error may be the dirty test tubes which may sway some reactions when solutions are mixed. Measurements may be another source of error. Such as using a plastic measuring cup can measure off by +/- 5%, and estimating the amount of solution in half a pipette. To improve this lab, and the Benedict test, another test should be done for non-reducing sugars that may give positive results. Another way to improve the lab is to use distilled water as a solution for comparision. The distilled water will not result in a positive control in the test due to the fact that water does not contain any macromolecules. The water can be compared with other solutions for a negative control. The results for iodine test indicate that solutions 1,2,3,4,5,6,9,10 and 11 turn yellow when mixed with iodine and therefore the solutions do not contain starch or glycogen. The yellow is a result from a colorless solution mixed with iodine. Solutions 7 and 12 turned red/brown when iodine was added. Conclusions can be made that these solutions contain glycogen. The highly branched structure reacting with iodine and gives it that red/brown color. Furthermore, solution 8 turned blue/purple which is an indication that it is starch, and it was also expected to result positive because it was 1% starch solution. Solution 7 therefore contains amylose and amyloepectin. But it is the amylose that initially reacts with iodine creating a blue color. Secondly, the results for the Benedicts test showed that solutions 2, 5, 7, 8, 9, 11 and 12 had a negative control. No color change. Therefore these solutions do not contain any molecules that can reduce cupic ions such as a reducing sugar. An