Testing for Macromolecules

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  • Topic: Protein, DNA, Biochemistry
  • Pages : 3 (1219 words )
  • Download(s) : 408
  • Published : April 18, 2009
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Abstract The aim of the experiment is to test the existence of macromolecules which are carbohydrates, lipids, nucleic acids and proteins in given samples. The first experiment is to test the existence of carbohydrates in starch suspension and potato cell. If carbohydrate is present in starch suspension, the solution will turn into dark blue when iodine solution is added. If carbohydrate is present in potato cell, starch granules can be seen clearly under microscope when iodine solution is added. The second experiment is to test the existence of lipids in margarine and olive oil. If a lipid is present in margarine, the solution suspended with alcohol will turn cloudy when it is mixed with distilled water. If a lipid is present in olive oil, the solution suspended with alcohol will become cloudier than the margarine ones when it is mixed with water. The third experiment is to test the existence of nucleic acids in the epidermis of an onion. If nucleic acid is present in the epidermis of the onion, the red-spot nucleus can be seen clearly when it is stained with aceto-orcein solution. The last experiment is to test the existence of proteins in cooked egg white. If protein is present in cooked egg white, the transparent solution of sodium hydroxide and cooked egg white will turn into purple when it is mixed with copper sulfate solution. Therefore, all macromolecules exist in all given samples. Introduction Macromolecules are large organic molecules which can be categorized into four major classes. They are carbohydrates, lipids, nucleic acids and proteins. Carbohydrates are the most abundant of these four macromolecules. Its basic units are called monosaccharide such as glucose, galactose and fructose. Monosaccharide can be linked together to form disaccharide and polysaccharide such as starch and cellulose. There are many functions of carbohydrates such as storage and transport of energy (starch) and structural component (cellulose). Lipids are defined as any...
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