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Proteins

Like the complex carbohydrates, proteins (or polypeptides) are large molecules made up of smaller subunits which have been bonded together. In this case, amino acids joined by peptide bonds.
Testing for Proteins

We used Biuret's reagent to detect the presence of proteins in solution. The reagent is pale blue when pure, but when mixed with proteins, the resulting reaction produces a pale purple color.

Left to right: Biuret's reagent (BrR), water + BrR, egg albumin solution, egg albumin solution+ BrR.

Terminology review: Controls

Water plus Biuret's reagent is a negative control for the protein test. It demonstrates a negative test result (no protein present).

Egg albumin plus Biuret's reagent is a positive control for the protein test. It demonstrates a positive test result (protein is present).

How would you set up similar controls for the other chemical tests?

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