Biochemical Analysis of Biomolecules - Introductory Biology - BSc. Biotechnology (HNRS)

 

Experiment No: 2 - Biochemical Analysis of Biomolecules

Objective:

To identify and analyze the presence of different biomolecules such as carbohydrates, proteins, and lipids in various samples using biochemical tests.

 

Materials:

• Test tubes
• Dropper pipettes
• Water bath
• Benedict's solution (for reducing sugars)
• Iodine solution (for starch)
• Biuret reagent (for proteins)
• Sudan III stain (for lipids)
• Ethanol (for lipid solubility test)
• Distilled water
• Food samples (e.g., glucose solution, starch solution, egg white, vegetable oil, potato, etc.)
• Test tube rack
• Hot plate or Bunsen burner (for heating)

 

Procedure:

1. Test for Reducing Sugars (Benedict's Test):

·         Sample Preparation: Place 2 ml of the food sample (e.g., glucose solution) in a test tube.

·         Add Reagent: Add 2 ml of Benedict's solution to the test tube.

·         Heat: Place the test tube in a boiling water bath for 5 minutes.

·         Observation: Observe any color change. A positive result will change the solution from blue to green, yellow, orange, or red, indicating the presence of reducing sugars.

2. Test for Starch (Iodine Test):

·         Sample Preparation: Place a small amount of the sample (e.g., potato or starch solution) on a clean white tile or in a test tube.

·         Add Reagent: Add a few drops of iodine solution to the sample.

·         Observation: Observe the color change. A blue-black color indicates the presence of starch, while no change indicates its absence.

3. Test for Proteins (Biuret Test):

• Sample Preparation: Place 2 ml of the protein sample (e.g., egg white) in a test tube.
• Add Reagent: Add 2 ml of Biuret reagent to the sample.
• Observation: Gently mix the contents and observe the color change. A violet or purple color indicates the presence of proteins. A blue color indicates the absence of proteins.

4. Test for Lipids (Sudan III Test and Ethanol Emulsion Test):

• Sudan III Test:

Sample Preparation: Place a small amount of the lipid sample (e.g., vegetable oil) in a test tube.

Add Reagent: Add a few drops of Sudan III stain to the sample.

Observation: Gently shake the test tube. A red-stained oil layer that separates from the water layer indicates the presence of lipids.

• Ethanol Emulsion Test:

Sample Preparation: Place a small amount of the lipid sample in a test tube.

Add Reagent: Add 2 ml of ethanol and shake the tube vigorously.

Add Water: Add 2 ml of distilled water to the test tube.

Observation: A milky-white emulsion indicates the presence of lipids, while a clear solution indicates their absence.

Conclusion:

The biochemical tests effectively identify the presence of key biomolecules in different samples. Benedict's test confirms reducing sugars, iodine test detects starch, Biuret test identifies proteins, and Sudan III and ethanol emulsion tests detect lipids. The observed results confirm the presence or absence of these biomolecules in the tested samples.

Precautions:

• Handle all reagents with care and follow safety protocols.
• Ensure test tubes are clean and dry before use to avoid contamination.
• Properly dispose of chemical waste according to lab safety guidelines.
• Heat samples carefully to avoid splashing or overheating.

This experiment provides a basic understanding of the biochemical composition of different substances and the methods used to detect essential biomolecules in various samples.

 

Observations:

Test	Sample	Expected Result	Observation
Benedict's Test	Glucose solution	Green, yellow, orange, or red precipitate
Iodine Test	Starch solution	Blue-black color
Biuret Test	Egg white	Violet or purple color
Sudan III Test	Vegetable oil	Red-stained oil layer
Ethanol Emulsion Test	Vegetable oil	Milky-white emulsion

Record your actual observations in the table above.