Identifying Biological Molecules with Colorimetric Chemical Tests
Objectives
Perform a series of accurate tests on biological molecules to detect the presence of carbohydrates and proteins, as well as the action of an enzyme on specific molecules.
Introduction
Unknown biological molecules can be correctly identified using various tests, including colorimetric chemical tests. Colorimetric tests are when a chemical reagent, such as Benedict’s, is used on a substance or solution and a certain color change occurs as a response. Carbohydrates and proteins, two of the larger types of biological molecules, also called macromolecules, are actually chains of molecules called polymers. The smaller molecules that build up these chains are…show more content… After exposure to boiled invertase all three had no reaction. The results from part 1 of Benedict’s Test before hydrolysis were used as comparison. These results were dH2O had no reaction, sucrose turned brownish-orange and raffinose turned an opaque reddish-brown.
PART 1. BIOLOGICAL MOLECULES TESTS | Test A. Benedict’s Test before hydrolysis | Test B. Benedict’s Test after hydrolysis | Test C. Lugol’s solution | Test D. Lugol’s solution after hydrolysis | Test E. Biuret’s Test | Tests for | Reducing sugars | Reducing sugars | Polysaccharides | Polysaccharides | Proteins | 1. dH2O | No Reaction | Blue/ No reaction | Yellow/ No reaction | Yellow/ No reaction | No reaction | 2. glucose | Dark orange | Brownish-orange | Yellow/ No reaction | Yellow/ No reaction | No reaction | 3. sucrose | No Reaction | Reddish-brown | Yellow/ No reaction | Yellow/ No reaction | No reaction | 4. raffinose | No Reaction | Light pink | Yellow/ No reaction | Yellow/ No reaction | No reaction | 5. starch | Yellow precipitate | Dark yellow-orange | blue-violet precipitate | Yellow/ No reaction | No reaction | 6. gelatin | Dark blue | Violet | Slightly opaque white | Yellow/ No reaction | Slightly violet w/ bubbles | 7. milk powder | Orange | Light yellow | No reaction/ No reaction | White precipitate & suspension | Slightly violet w/ bubbles | 8. egg albumin | Light greyish blue | Grey violet | No reaction/ No reaction | Large am. of white
