Macromolecule Virtual Lab

Watch the you-tube video and answer the below questions: Please type. No hand-writing accepted (except for drawings)

Carbohydrates, proteins, fats, vitamins, and other nutrients provide your body with energy and provide the raw materials necessary to carry on life activities. These compounds are present in the plants and animals you use as food. The most common organic compounds found in living organisms are lipids, carbohydrates, proteins, and nucleic acids. Common foods, which often consist of plant materials or substances derived from animals, are also combinations of these organic compounds. Substances called indicators can be used to test for the presence of organic compounds. An indicator is a substance that changes color in the presence of a particular compound. In this investigation, you will use several indicators to test for the presence of lipids, carbohydrates, and proteins in various foods.

Reagents:

Benedict’s solution: tests for sugar (carbohydrates) Biuret solution: tests for protein

Lugol’s iodine solution: tests for starch (complex carbohydrates) Sudan III solution: tests for lipids

Pre-Lab Questions: What are Biomolecules?

1. List the four biomolecules and provide examples of foods that contain them.

• What is a chemical indicator?

• For this lab, what were the chemical indicators used and what was their function?

• Which types of biomolecules do you predict that you will find in a potato, orange juice, almonds, eggs, salmon and milk? Explain your prediction.

Food Substance	Prediction	Explanation
Potato
Orange Juice
Nuts
Eggs
Salmon
Milk

• How are monomers and polymers different?

• What are the monomers for each of these macromolecules?
  • Carbohydrates: b) Nucleic Acids:

              c) Proteins:                                                          d) Lipids (fats):

• Circle any of the following compounds that would be classified as carbohydrates.
  • Amino acids b) Fructose c) Maltose d) Glucose

               e) Starch                                                           f) Hemoglobin                                                          g) Lactose

CARBOHYDRATES

1. What are three examples of carbohydrates?

• How do you test for sugars?

Benedict’s solution is added to the test tube. When heated, Benedict’s solution will change color from blue to green, yellow, orange, or red in the presence of a simple sugar, or monosaccharide. The more sugar present, the more orange/red the solution should be.

1. What was the color of the solution in the test tube?

• How did the solution changed colors after being in hot water?

Iodine will change color from yellow-brown to blue-black in the presence of starch.

1. What chemical is being added to the test tubes?

• What should happen if starch is present

PROTEINS

Biuret reagent changes color from yellow to blue-violet in the presence of protein.

1. What test do we use to test for proteins?

Draw the lab set-up and label the different test tubes for the Biuret’s reaction.

LIPIDS

Sudan IV stain will dissolve in lipids and stain them red or orange.

1. What test is used for lipids?

• How does it work?

Analysis Questions:

1. Match the molecule to the chemical used to test for it to the color that the chemical would change for a positive test.

Macromolecule	Reagent	Color Change
Sugar	Biuret Reagent	Green, Orange, or Red color
Protein	Sudan III	Blue-black color
Lipid	Iodine	Red or Orange color
Starch	Benedict’s Solution	Blue-Violet color