Detection of biological molecules. Lab work.

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very extensive lab... the results should be obtained by the reader who should have the info. good style and observations.


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.


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,