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Identifying different biological macromolecules

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IDENTIFYING DIFFERENT BIOLOGICAL MACROMOLECULES Introduction Biological macromolecules consist of very small organic molecules that are linked together to produce large molecules (Garcia, 2002). These large molecules are called polymers (Garcia, 2002). In particular, for macromolecules like carbohydrates and proteins, the polymer molecule is created when small molecules called monomers are covalently bonded to one another (Garcia, 2002). There are four major types of biological macromolecules. The four groups are carbohydrates which consist of polysaccharides and monosaccharides, proteins, lipids and nucleic acids (Garcia, 2002). Biological macromolecules are relevant because they are the building blocks of cells in both animals and plants (Karp, 2010). These types of molecules not only form the structure of a cell, but also carry out the cells' activities (Karp, 2010). The existence of macromolecules in living organisms is what provides life and separates them from the rest of the world (Karp, 2010). The purpose of this experiment is to test for the presence of macromolecules in various liquid solutions. In this lab we will explore two of the four types: carbohydrates and proteins. In carbohydrates the monomer unit is called a simple sugar while in proteins the monomers that are linked together are called amino acids (Garcia, 2002). Particularly, in carbohydrates when a simple sugar is present it is referred to as a monosaccharide and when a bunch of monosaccharides are attached to one another covalently a complex sugar is formed known as a polysaccharide (Garcia, 2002). ...read more.


If the colour of the solution turns yellow then the test is negative and there is no presence of starch or glycogen (Garcia, 2002). The Benedict's test is used to test for the presence of a monosaccharide called glucose in the solutions (Garcia, 2002). To test for the presence of glucose a clear blue liquid known as Benedict's reagent is used which contains copper (+2) ions (Garcia, 2002). When this reagent is mixed and boiled with any solution containing trace amounts of glucose the copper (+2) ions reduce to copper (+1) ions and then become oxidized to form copper oxide (Garcia, 2002). In Benedict's test a positive test is when the colour of the solution changes to a red-brown or orange-brown when the reagent is added (Garcia, 2002). The Biuret test is used to test for the presence of protein molecules in solution (Garcia, 2002). To test for the presence of protein, a liquid known as Biuret reagent which also contains copper ions is added to a solution (Garcia, 2002). When the reagent is added to solution the coppers ions react with the linked protein groups to produce a violet colour (Garcia, 2002). In the Biuret test the only colour that signals a positive test result is the colour violet (Garcia, 2002). ...read more.


The solutions that resulted in negative control were glucose, glucose-1-phosphate, maltose, honey, sucrose, lactose, glycogen, starch, beer, distilled water and the unknown (215) solution. Discussion Looking at the results from the Buiret test, the only solution that had a positive control was protein because no other solution contained any trace amounts of protein macromolecules except for the obvious protein solution. Looking at the results from the iodine test the obvious solutions that had positive results were 1% glycogen and 1% starch because they contained carbohydrate polysaccharide molecules (Miskovic, 2011). For the Benedict's test the solutions that were positive were glucose, maltose, honey, lactose, beer, and unknown (215). These solutions had positive results because they contained simple sugars within the solutions (Miskovic, 2011). Overall, the results were what I expected except for the 1% sucrose solution involved in the Benedict's test. I predicted that sucrose would have a positive result and contain trace amounts sugar molecules, but instead I ended up with a negative result during the experiment. Referring back to the experiment the unknown solution is 1% starch solution because looking at the iodine test for starch and glycogen the unknown solution had the same type of control and colour as the 1% starch solution. Both solutions had a positive test control and both solutions were bluish-black after the test was complete therefore it can be concluded that the unknown (215) solution is indeed 1% starch solution. ...read more.

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