Explain Biochemical test for Glucose, Protein and Lipids and Their positive test results.
To test the presence of glucose, Benedict's reagent is used. Benedict reagent is a blue solution. In the presence of this solution, glucose changes its colour to green or yellow or red.
To test the presence of protein, incubate the sections in acid fuchsin reagent for 10 min. Wash and mount a section in glycerin. Cellular inclusions turn red showing the presence of protein.Bromophenol blue reagent is also used for protein test.
To test the presence of lipids, take the material on slide and put a few drops of sudan III. A red colour will appear.
To test for simple carbohydrates such as glucose, you would use Benedict's solution. Benedict's solution is an indicator for simple sugars. If the color is an aqua blue, then the result is negative for simple sugars. If you get a yellow/green/red color, then the result is positive for simple sugars. Unlike many indicators, Benedict's solution does not work at room temperature and must be heated prior to taking results.
To test for a complex carbohydrate such as starch, you would use Iodine solution. In the presence of starch, the iodine would be black/blue.
To test for proteins (amino acids, the building blocks of proteins), you would use biuret solution. A negative test would show a blue color and a positive test would result in a violet blue to a pink purple color.
To test for lipids you would use Sudan IV. A negative result would be dark red and a positive test for lipids would show a red/orange color.