Detection of Biological Molecules
Detection of Biological Molecules
Introduction: Without carbon, nitrogen, hydrogen, sulfur, oxygen and phosphorus, life wouldn't exist. These are the most abundant elements in living organisms.
These elements are held together by covalent bonds, ionic bonds, hydrogen bonds, and disulfide bonds. Covalent bonds are especially strong, thus, are present in monomers, the building blocks of life. These monomers combine to make polymers, which is a long chain of monomers strung together. Biological molecules can be distinguished by their functional groups. For example, an amino group is present in amino acids, and a carboxyl group can always be found in fatty acids.
The groups can be separated into two more categories, the polar, hydrophilic, and the nonpolar, hydrophobic. A fatty acid is nonpolar, hence it doesn't mix with water. Molecules of a certain class have similar chemical properties because they have the same functional groups. A chemical test that is sensitive to these groups can be used to identify molecules that are in that class. This lab is broken down into four different sections, the Benedict's test for reducing sugars, the iodine test for the presence of starch, the Sudan III test for fatty acids, and the Biuret test for amino groups present in proteins. The last part of this lab takes an unknown substance and by the four tests, determine what the substance is.
BENEDICT'S TEST
Introduction: Monosaccharides and disaccharides can be detected because of their free aldehyde groups, thus, testing positive for the Benedict's test.
Such sugars act as a reducing agent, and is called a reducing sugar. By mixing the sugar solution with the Benedict's solution and adding heat, an oxidation- reduction reaction will occur. The sugar will oxidize, gaining an oxygen, and the Benedict's reagent will reduce, losing an oxygen. If the resulting solution is red orange, it tests positive, a change to green indicates a smaller amount of reducing sugar, and if
Introduction: Without carbon, nitrogen, hydrogen, sulfur, oxygen and phosphorus, life wouldn't exist. These are the most abundant elements in living organisms.
These elements are held together by covalent bonds, ionic bonds, hydrogen bonds, and disulfide bonds. Covalent bonds are especially strong, thus, are present in monomers, the building blocks of life. These monomers combine to make polymers, which is a long chain of monomers strung together. Biological molecules can be distinguished by their functional groups. For example, an amino group is present in amino acids, and a carboxyl group can always be found in fatty acids.
The groups can be separated into two more categories, the polar, hydrophilic, and the nonpolar, hydrophobic. A fatty acid is nonpolar, hence it doesn't mix with water. Molecules of a certain class have similar chemical properties because they have the same functional groups. A chemical test that is sensitive to these groups can be used to identify molecules that are in that class. This lab is broken down into four different sections, the Benedict's test for reducing sugars, the iodine test for the presence of starch, the Sudan III test for fatty acids, and the Biuret test for amino groups present in proteins. The last part of this lab takes an unknown substance and by the four tests, determine what the substance is.
BENEDICT'S TEST
Introduction: Monosaccharides and disaccharides can be detected because of their free aldehyde groups, thus, testing positive for the Benedict's test.
Such sugars act as a reducing agent, and is called a reducing sugar. By mixing the sugar solution with the Benedict's solution and adding heat, an oxidation- reduction reaction will occur. The sugar will oxidize, gaining an oxygen, and the Benedict's reagent will reduce, losing an oxygen. If the resulting solution is red orange, it tests positive, a change to green indicates a smaller amount of reducing sugar, and if