Part A Macromolecule Virtual Lab Go to the website: http://faculty.kirkwood.edu/apeterk/learningobjects/biologylabs.htm CARBOHYDRATES Scroll down to the bottom and click on Carbohydrate 1. What do carbohydrates consist of? 2. Plants store carbohydrates as 3. Insects store carbohydrates as 4. How do you test for sugars? How does it work? Click on Add Benedict s Reagent Click on Hot Water Bath 1. Which solutions changed colors? 2. What does this mean? Click on the scroll down bar on the right hand side and go to starches 3. How do you test for starches? How does it work? 4. Which solutions changed colors? 5. What does this mean? PROTEINS Click on the tab marked protein 1. What are the chains that make up proteins? 2. What test do we use to test for proteins? How does it work? 3. What solutions changed color? What does it mean? 1
LIPIDS Click on tab marked Lipids 1. What test is used for lipids? 2. How does it work? 3. What color do the solutions change if lipids are present? Click on add Sudan III 4. What solutions changed colors? 5. What does this mean? EVERYDAY FOODS Click on the tab marked Everyday Foods Choose the gelatin sample to test first Click on the tab marked Everyday Foods Choose the Apple Juice sample to test 2
Choose the Ritz Cracker sample to test Choose the Skim Milk sample to test first Analysis Questions: 1. What is the purpose of this lab? 3
Part B Biomolecules in Food Read through the lab and fill in the following information Purpose: Pre-lab questions: 1. How do you know if a food contains protein? 2. How do you know if a food contains starch? 3. What is the difference between starch and sugar? Procedure: Part 1 Testing for Carbohydrates (Polysaccharides- Starch) 2. Use a dropper or the tweezers to place a small amount of the food item into each of the test tubes. (5 drops) 3. Add 1-2 drops of Iodine to the test tube. 4. Observe the test tube, if the food contains starch it will turn a blue- black color. If the color remains brown, no starch is present. ***Put a if starch is present an X if not present in your data table 5. Empty the test tube into the sink and rinse with water. Part 2 Testing for Carbohydrates (monosaccharides- sugar) 6. Use a dropper or the tweezers to place a small amount of the food item into each of the test tubes. (5 drops) 7. Add 5 drops of Benedict s solution to the test tube 8. Carefully place the test tubes into the hot water bath. Heat the tube for 2-3 minutes. (Use a test tube holder to remove the tubes from the hot water.) 9. Observe the test tube, look at the following table to determine the quantity of sugar in the food. ***Identity if sugar is present by writing the color and how much is present in your data table. Amount of sugar in food None Trace amounts Little Sugar Some Sugar A lot of sugar Color Blue/Purple Blue/green Green Yellow Orange Red 10. Empty the test tubes into the sink and rinse with water. Part 3 Testing for Protein 11. Use a dropper or the tweezers to place a small amount of the food item into each of the test tubes. (5 drops) 12. Add 5 drops of biuret reagent to your tubes (Biuret can burn your skin- wash off spills with lots of water.) 13. Observe the test tube, if the food contains protein it will turn a pinkish-purple. ***Put a if protein is present an X if not present in your data table 14. Empty the test tube into the sink and rinse with water. 4
Part 4 Testing for Lipids 15. Use a dropper or tweezers to place a small out of substance onto the brown paper. If the food is a solid, rub onto the brown paper. 16. Wait for 2 mins, remove any large pieces of food and observe. 17. Look at the paper against a light source. There are lipids present if a lot of light can pass through the paper. If little or no light can pass through then there is little or no lipids present. ***Put a if lipid is present an X if not present in your data table DATA 18. Throw the piece of paper away. Food Lipids Protein Starch (polymer) 1.Water Sugar (monomer) 2.Potato Water 3.Dextrose (Sprite) 4.Vegetable Oil 5.Gelatin 6.Egg White 5
Post lab questions 1. Which foods come from plants? What biomolecule is most common in these foods? 2. Which foods come from animals? What biomolecule is most common in these foods? 3. Does water contain any of the macromolecules that you tested for? Explain why water is used as a control. 4. Fill out the following table by listing the foods that you tested. Carbohydrates Protein Lipids 5. Most macromolecules are made from chains of much simpler molecules (subunits). Name the subunits that link up to form the following macromolecules and draw a picture of each one. Name one food source for each macromolecule. Macromolecule Food Source Name the Monomer Picture of Monomer Carbohydrates Nucleic Acids Proteins Lipids 6