Macromolecules Lab Biology

Bell Work! 1) What are the four macromolecules? 2) Which macromolecules stores energy? 3) List one important function of Carbohydrates.

Macromolecules We have been working on macromolecules all week so you should have a pretty good idea of what they are by now. We will be performing tests in the lab today to identify 3 out of the 4 macromolecules.

Objective; Students will be able to: Successfully identify the 3 different macromolecules using tests in the lab. Tests we will be performing: Iodine test for Carbohydrates Biuret Test for Proteins Grease-Spot test for lipids

Identifying an Unknown: You have 3 large test tubes in front of you. 1) Is a mixture of egg protein and water. 2) Is a mixture of starch and water. 3) Is an unknown. Your objective is to identify which ones are which by performing tests in the lab today!

Lab Safety: 1) Remember, you cannot do this lab unless you have turned in your safety contract. 2) No Food or drink while working on the lab! 3) Always wear your goggles throughout the whole lab because we will be working with chemicals that are dangerous. 4) You must wear gloves in this experiment. If you have a latex allergy, let us know, we have other gloves. 5) We will be working with sodium hydroxide solution that will burn you if it comes in contact with your skin. 6) We will be working with copper solution and iodine that will dye your hands and clothes blue or brown if they come in contact.

Step #1 1) There are 6 smaller test tubes, label them 1-6 with the marker on your table. 2) Separate each large test tube into two smaller test tubes 3) To separate the large test tubes, place about 1cm of liquid in each smaller test tube. 4) Separate large test tube 1 into smaller test tubes 1 and 2. 5) Separate large test tube 2 into smaller test tubes 3 and 4. 6) Separate large test tube 3 into smaller test tubes 5 and 6. 7) Be careful to label and not mix up your test tubes!

Steps (Continued) 8) Please work with the person sitting next to you at your lab station. Each group will perform their own tests. 9) Follow the instructions on the handout completely so you perform the procedures correctly. 10) You should have all of the items you need on your lab station but please don’t hesitate to ask if you are unsure about something. 11) And always remember, BE SAFE!

Test 1: Iodine Test for Starch (Carbohydrates) 1) Add 3-5 drops of Iodine to test tubes 1, 3, and 5. 2) Record the color of the tubes in the table provided. 3) A positive test for starch will be a bluish-black color. 4) A negative test will be a yellowish-brown color.

Test 2: The biuret test for Proteins 1) Add 2mL of 2.5% sodium hydroxide (clear solution) to tubes 2, 4, and 6. 2) Add 3 drops of Copper solution (the blue solution) to tubes 2, 4, and 6 and mix. 3) Record the color of the tubes in the table provided. A positive result will be a violet (purplish) color.

Proteins Tube # Positive Negative

Carbohydrates Tube # Positive Negative

Results Tube # Contents Tube #1 Tube #2 Tube #3 Based on your results which test tube is the protein solution, which one is the carbohydrate, and which one is the unknown? Tube # Contents Tube #1 Tube #2 Tube #3

Test 3 : The Grease-spot test for Lipids 1) Take the piece of construction paper from up front and place a drop of oil near the corner of the piece of paper. 2) Add a drop of water near the opposite corner of the paper. 3) Let the fluids dry. 4) Once they are dry, hold the paper up to the light. 5) Record your data on your lab sheet. The oil should produce translucent grease marks on the paper.