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 turn reddish/brown due to the multibranched nature of glycogen. Forms of carbohydrates are mono and polysaccharides. Both glycogen and starch are a form of a polysaccharide structure, but differ in their shape and branching. Glycogen is highly branched while starch contains amylose (unbranched) and amylopectin ( branched). Furthermore, the Benedicts test is done to discover reducing sugars in solutions. Simple straight chained sugars contain an aldehyde group which reacts with the Cu+ ions from the benedicts solution. For the benedict test to work, the mixed solution must be heated. If the solution contains a precipitate ranging from many colors, that solution contains reducing sugars. The last test done is the biuret test to discover the presence of proteins. Proteins are built in the form of long polymer chains that consist of amino acids. There are 7 essential amino acids which come from only the foods that are consumed. 13 amino acids are already available inside the human body. The biuret test will result in the solution turning violet if Cu++ ions react with peptide bonds. Peptide bonds are bonds that link amino acids to create protein. During the experiment, there will be positive and negative controls. A positive control will conclude in a positive result if procedures are followed. A negative control results in a negative result if the expermint ws properly done. Materials and Method
( Biology Department, 2013 )
Table 1: Qualitative Observation During Iodine Test For Starch and Glycogen Solution ( 15 ml ) Solutions Color Iodine added 1) 1% glucose clear Yellow 2) 0.3% glucose-1-phosphate clear Yellow 3) 1% maltose clear Yellow 4) Honey solution clear Yellow 5) 1% sucrose clear Yellow 6) 1% lactose clear Yellow 7) 1% glycogen clear Red/brown 8) 1% starch clear Blue 9) Protein clear Yellow 10) beer clear Yellow 11) Distilled water clear Yellow 12) Unknown clear Yellow Link: If starch is present, the solution will turn blue, while...
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[The nature of glycogen complexing with iodine in... [Biokhimiia. 1986] - PubMed - NCBI. (n.d.). National Center for Biotechnology Information. Retrieved September 21, 2013, from http://www.ncbi.nlm.nih.gov/pubmed/2423143
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