SCIENCE 101 Identify the positive and negative controls

12 Jun SCIENCE 101 Identify the positive and negative controls

Question
Experiment 2: Testing for Proteins

Data Tables and Post-Lab Assessment

Table 1: Protein Presence Predictions

SAMPLE WITH TEST TUBE NUMBER
Initial Color of Solution

Will There be Protein Present?

Final Color After Biuret Solution is Added

1 – Albumin Solution

Light Blue

Yes

Violet

2 – Gelatin Solution

Light Blue

Yes

Violet

3 – Glucose

Light Blue

No

Light Blue

4 – Water

Light Blue

No

Light Blue

5 – Unknown

Light Blue

Yes

Light Violet

Table 2: Protein Presence with Biuret Solution Results

SAMPLE WITH TEST TUBE NUMBER
Initial Color of Solution

Final Color After Biuret Solution is Added

Protein Present?

1 – Albumin Solution

Purple

Dark violet/purple

settled on bottom of

test tube

Yes

2 – Gelatin Solution

Violet

Violet

Yes

3 – Glucose

Light Blue

Light Blue

No

4 – Water

Light Blue

Light Blue

No

5 – Unknown

Light Blue

Milky Blue

No

Post-Lab Questions

1. How did your predictions from Table 1 compare to your actual results in Table 2? If there were any inconsistencies, explain why this occurred.

My prediction was correct except for the unknown solution.

2. Identify the positive and negative controls used in this experiment. Explain how each of control is used, and why they are necessary to validate the experimental results.

Positive control- gelatin solution since gelatin is high in protein; it will definitely show a color change.

Negative control- glucose solution Glucose does not contain protein so no color change will occur.

These controls are used so that we can assure that the reactant, Biuret solution, is working correctly. They are necessary so we can ensure the reactant is working and assume that theother results are accurate.

3. Write a statement to explain the molecular composition of the unknown solution based on the data recorded in Table 2.

4. What can you conclude about the molecular make-up of egg whites? Use your results to support your answer.

5. What is the name of a common macromolecule in egg white that would react with the Biuret solution?

6. What can you conclude about the molecular make up of gelatin? Use your results to support your answer.

7. What is the name of a common type of macromolecule found in gelatin that would react with the Biuret solution?

8. How might extreme hot temperature affect the molecular composition of eggs?

9. What can you conclude about the molecular make-up of the glucose solution? Use your results to support your answer.

10. Glucose is one of the main sugars absorbed during digestion. What type of macromolecule is glucose derived from?

11. Hemoglobin is a protein that is vital to humans. What results would you expect if a hemoglobin solution was tested with Biuret solution?

12. What major function does hemoglobin perform?

13. Sickle cell disease is caused by a mutation in hemoglobin. Research and discuss the structural effect on mutated hemoglobin proteins.