The Cell
First Name
Last Name
State Standard:
H.1L.1 -- Compare and contrast the four types of organic
macromolecules. Explain how they compose the cellular structures of organisms
and are involved in critical cellular processes.
10
8
6
4
1
Response
Excellent
Proficient
Adequate
Incorrect
incomplete
Scoring Rubric 1-4
Responses are clear, complete and demonstrate a thorough understanding of the subject matter
Completes the assignment or experiment satisfactorily, but the explanations have minor flaws
Begins the assignment and explanation satisfactorily; but omits significant parts or fails to complete.
Assignment and its explanations are not accurate. Group did not demonstrate understanding or authentic knowledge
Did not participate
Score
Lab: Characteristics of Fats and Proteins
All foods contain some of the six nutrients (proteins, fats, carbohydrates, water, vitamins and minerals).
However, you cannot tell what nutrients are in food by looking at the food. You can tell if certain nutrients are
present by doing certain tests. This activity will let you test a number of different foods to find out if fats and
proteins are present.
Pre-Lab
1. What is a control group? ____________________________________________________________
2. What is a fat? ____________________________________________________________________
3. What is a nutrient? ________________________________________________________________
4. What is a protein? _________________________________________________________________
5. What does “translucent” mean?______________________________________________________
Materials
*brown paper, cooking oil, 8 droppers, test tube rack, 8 stoppers, Biuret solution, 8 test tubes, foodstuffs, wood
splints
Fat water
Procedure PartA
1. Use a dropper to place one small drop of cooking oil (fat) onto
a piece of brown paper. Label the drop “fat”.
2. Rub the drop around on the paper, making a circular area (fig. 1)
3. Use a different dropper to place one small drop of water onto the
Fig. 1
piece of brown paper away from the oil spot. Label the spot “non-fat”.
4. Using a NEW finger, rub the drop around on the paper, making a circular area.
Food
Translucent?
Fat present?
5. Wait a few minutes of the liquids to dry. You can speed
Oil
(fat)
up the drying time by waving the paper in the air.
Water (non-fat)
6. Hold the paper up toward the light. If light passes
Butter
through the oil spot, it is said to be translucent. Fat forms a
Egg white (solid)
translucent spot on brown paper.
Peanut butter
7. Record your results in table 1.
Table 1
Hamburger
Mayonnaise
Cheese
Lard
Testing a Protein and
Apple
a non-protein Part B
1. Add 5 drops of egg white liquid (a protein) to a test tube. Label this “protein”
2. Add 5 drops water to a second test tube. Label this tube “water”.
3. Label a third test tube “Biuret”
4. Add 5 drops Biuret solution to each of the three test tubes. Caution: if the Biuret solution is spilled, wash it
off your hands or clothing immediately.
5. Place a stopper into the first two test tubes. Shake both tubes gently for one minute.
6. Compare the color of all three tubes. Biuret solution forms a purple color when mixed with protein.
7. Record results in Table 2.
Tube number and/or contents
Egg white liquid (protein) + Biuret
Water (non-protein) + Biuret
Biuret Solution
1. Biuret
2. Biuret + cheese
3. Biuret + lard
4. Biuret + hamburger
5. Biuret + chicken
Table 2
Color w/Biuret solution
Protein present?
Testing Foods for Protein Part C
1. Number five test tubes in a test tube rack
2. Add the following to each tube using Fig. 2 as a guide. Sticks may be used to add very small amounts of
each food (about the size of ½ a pea) to each tube:
Tube 1: 5 drops of Biuret solution
Tube 2: 5 drops of Biuret solution and cheese
Tube 3: 5 drops of Biuret solution and lard
Tube 4: 5 drops of Biuret solution and hamburger
Tube 5: 5 drops of Biuret solution and chicken
3. Place a stopper in tubes 2-5. Shake tubes 2-5 for 1 minute.
4. Compare color of the solution in tubes 2-5 with tube 1.
5. Record results in table 2.
Questions
1. Describe how you can test for the nutrient fat in foods?
2. Why was it helpful to first test a food that you were told already had fat in it?
3. Why was it helpful to compare the spot left by fat to the spot left by water?
4. Which foods contained fat?
5. How is the nutrient fat used in the body?
6. Your friends lunch bag has a large translucent spot at the bottom. How would you explain this?
7. Describe how you can test for the nutrient protein in foods?
8. How is protein used in the body?
9. Why was it helpful to compare the color in a tube that contained protein to the color in a tube that did not
contain protein?
10. Which foods contained protein?