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Biological Molecules: Carbohydrates, Lipids, Proteins
By the end of this lab, the student should be able to:

Identify the functional groups for each of the biomolecules that react in the following biochemical tests: Benedict’s test, Iodine test, Brown Bag test, Sudan III/IV test, and the Biuret's Test.

Describe the mechanism of reaction for: Benedict’s test, Iodine test, Sudan III/IV test, and the Biuret's Test.

Interpret the results when presented with data for each of the biochemical tests.

Design experiments to identify biomolecules using biochemical tests.
Introduction
Biological Molecules contain specific chemical structures called functional groups, which can be distinguished by biochemical tests, such as Benedict's Iodine, and Sudan III/IV. The Benedict's test identifies reducing sugars (monosaccharide's and some disaccharides), which have free ketone or aldehyde functional groups). The groups reduce CuSO4, a component of Benedicts, resulting in a color change in the benedicts solution from a turquoise to a brick to rusty-brown color. Another class of carbohydrates called starches, a polysaccharide, can be detected using the Iodine's test. Having a high molecular weight, iodine attaches to the helical structure of starches yielding a blue-black precipitate. The Biuret's test identifies proteins by oxidizing 4-6 peptide bonds of a protein using CuSO4 and NaOH resulting in a color change in the CuSO4 solution from purple to a darker purple color. Finally, the Sudan III/IV test is used to detect the hydrocarbon chains of lipids. Sudan is a red, non-polar, dye that forms hydrophobic interactions with the hydrocarbon chains of lipids. Alternatively, the Brown Bag test can also be used to identify lipids due to the oily nature of hydrocarbon chains.
Carbohydrates: Reducing sugars and starches
Reducing Sugars
Some sugars such as glucose are called reducing sugars because they are capable of transferring hydrogens (electrons) to

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