Who Took Jerrell S Ipod

http://serendip.brynmawr.edu/exchange/waldron/organic

Who Took Jerrell’s iPod? An Organic Compound Mystery -- Part 1 Adapted by Jennifer Slavick, Roxborough High School, Philadelphia, from Dr. Jennifer Doherty and Dr. Ingrid Waldron, Department of Biology, University of Pennsylvania, copyright 2009 Adapted from “Identity of Organic Compounds” from Biology Laboratory Manual A from Prentice-Hall; Also inspired by “Crime Scene Activity” by Kathy Paris, Bethel High School

Name: ______What are organic compounds? Almost all of the food we eat comes from plants and animals. Plants and animals contain mainly water and organic compounds, which are molecules made by living organisms such as plants or animals. The table below lists the most common types of organic compounds found in living organisms.

For each type of organic compound, give two examples and describe the defining characteristic of each.

Type of Organic Two Examples Defining Characteristic Compound Carbohydrates

Lipids

Nucleic Acids

Proteins

Today you will be testing the substances listed in the following table. Predict what type of organic compound each test substance is.

Do you think this substance is a carbohydrate, lipid, Substance protein, or none of these? Vegetable oil Glucose (sugar) Starch from potatoes Powdered egg whites Water

What are indicators? An indicator is a substance that changes color in the presence of a particular type of compound. Today you will learn how to use several indicators to test for the presence of carbohydrates and proteins. You will also use a different type of test for lipids. In your next class, you will use these tests to analyze several types of food and the evidence left at the scene of a crime. http://serendip.brynmawr.edu/exchange/waldron/organic

Procedure Testing for lipids 1. If a food that contains lipids is put on brown paper, it will leave a spot that lets light through. To test for lipids, divide a piece of brown paper bag into 5 sections. Label the sections “vegetable oil,” “glucose,” “starch,” “egg whites,” and “water.” 2. In each section, rub a small amount of the substance onto the brown paper bag. 3. With a paper towel, rub off any excess that may stick to the paper. Set the paper aside until the spots appear dry – about 10-15 minutes. 4. Which section do you expect to test positive for lipids?

5. Which sections do you expect to test negative for lipids?

6. Continue on with the rest of the tests. After all the sections of the brown paper are dry, hold it up to a bright light or window. Sometimes it is easier to see the results through the back of the paper. You will notice that at least one sample has left a spot that lets light through on the brown paper. The spot indicates the presence of lipids. Record your results in the table.

Lipid Carbohydrate Test Protein Test Test Sample Test Glucose Iodine Starch Biuret Protein Lipid Strip Present Test Present Test Present Present Color +/-? Color +/-? Color +/-? +/-? Vegetable oil Glucose Starch from potatoes Powdered egg whites Water

Testing for Carbohydrates 1. Today you will be using chemicals as indicators. You must wear gloves to protect yourself. 2. Glucose and starch are two common types of carbohydrates that you can test for by using indicators. Obtain one container of each “vegetable oil,” “glucose,” “starch,” “egg whites,” and “water.” 3. For each container, take a small amount in a spoon, add a little bit of water, and thoroughly mix. Be sure to use one spoon per sample. http://serendip.brynmawr.edu/exchange/waldron/organic

4. To test for glucose, a specific type of sugar, you can use a test strip that changes color in the presence of glucose.

The strip turns brown if glucose is present.

Dip one test strip in each sample for 2 seconds. Remove the strip and set it on the brown paper bag in its properly labeled section and wait 3 minutes. 5. Which substance did you expect to test positive for glucose?

6. Which substances do you expect to test negative for glucose?

7. After 3 minutes, record the color for each glucose test strip in the data table above. Put a plus next to those samples testing positive for glucose and a minus for those testing negative. 8. To test for starch you will use iodine as an indicator. In the presence of starch, iodine will change from yellow or brown to black or dark blue. 9. Put a small sample of each substance on its spoon. Add five drops of iodine to each spoon and swirl it around. CAUTION: Be careful when handling iodine. It will stand your hands and your clothes. 10. Record the color of the iodine solutions in the data table. Put a plus next to those samples testing positive for starch and a minus for those testing negative.

Testing for Proteins 1. Rinse of each spoon and wipe clean with a paper towel. Do not mix up your spoons. 2. Add a small amount of each substance to your spoon. 3. To test for protein, you will use a new indicator. Biuret reagent turns from blue to purple in the presence of protein. 4. Add five drops of biuret reagent to each spoon and swirl it around. CAUTION: Biuret reagent contains sodium hydroxide, a strong base. Be very careful not to splash or spill any. If you splash any reagent on yourself, wash it off immediately with water. Call your teacher for assistance. 5. Which substances do you expect to test positive for protein?

6. Which substances do you expect to test negative for protein?

7. Record the color of each solution in the data table. Put a plus next to those samples testing positive for protein and a minus for those testing negative. http://serendip.brynmawr.edu/exchange/waldron/organic

8. Check back with your lipid test on the brown paper. After all the sections of the brown paper are dry, hold it up to a bright light or window. Sometimes it is easier to see the results through the back of the paper. 9. You will notice that at least one sample has left a spot that lets light through on the brown paper. The spot indicates the presence of lipids. Record your results in the table. 10. Rinse all of the spoons and containers thoroughly. Wipe each dry with a paper towel and set aside.

Questions

1. Compare your predictions in the table on page 1 with your test results in the table on page 2. Were there any differences between your test results and your predictions for what type of organic compound each test substance is?

2. If you found any differences between your predictions and results, what do you think is the reason for these differences? You may want to check with your teacher or your textbook to help you interpret your results.

3. Suppose that for the spoon containing water you found a positive test for one of the organic compounds. How would you interpret this result?

4. Suppose that you found a large spot that lets light through light on the bottom of your paper lunch bag. What explanation could you give for this spot? http://serendip.brynmawr.edu/exchange/waldron/organic

Who Took Jerrell’s iPod? An Organic Compound Mystery -- Part 2 Adapted by Jennifer Slavick, Roxborough High School, Philadelphia, from Dr. Jennifer Doherty and Dr. Ingrid Waldron, Department of Biology, University of Pennsylvania, copyright 2009 Adapted from “Identity of Organic Compounds” from Biology Laboratory Manual A from Prentice-Hall; Also inspired by “Crime Scene Activity” by Kathy Paris, Bethel High School

Name: ______

Jerell is a 10th grade student at City High School who works at McDonald’s on the weekends. While on break, Jerrell was studying for his biology test and listening to his new iPod. There were four other workers taking a break at the same time, each having something different for lunch.

Jerrell’s girlfriend stopped by near the end of his break, and he rushed out to see her and forgot his iPod and biology book in the break room. When he realized, he hurried back and found only his biology book and some food crumbs. His iPod was gone!

First Jerrell freaked out, but he calmed down when he realized he could use his knowledge of organic compounds to figure out which of his coworkers left the crumbs on his textbook and who took his iPod.

Part I: Testing Possible Foods

1. Predict what types of compounds you expect to find in each type of food you will be testing. Think about each food and complete the table below by putting in Yes or No.

Do you expect this food to contain… Food Glucose? Starch? Protein? Lipid? Pretzel Butter Jelly Fat-free Yogurt Beans

2. Use the procedure from yesterday to test each food. Record the results in the table on the next page. http://serendip.brynmawr.edu/exchange/waldron/organic

Lipid Carbohydrate Tests Protein Test Test Food Test Glucose Iodine Starch Biuret Protein Lipid Strip Present? Test Present? Test Present? Present? Color +/- Color +/- Color +/- +/- Pretzel Butter Jelly Fat-free Yogurt Beans Jerrell’s Evidence

Questions

1. Compare your predictions in the table on page 1 with your results in the table above. Were there any differences?

2. If you found differences between your predictions and your results, what do you think is the reason for these differences? You may want to check with your textbook or consult your teacher to help you interpret results.

Part II: Who Took Jerrell’s iPod?

The workers in the break room are listed below with the type of lunch they were eating while Jerrell was studying.

As preparation for interpreting the evidence, complete the chart below to indicate what kinds of organic compounds are found in each type of food and what kinds of organic compounds were found in the evidence. http://serendip.brynmawr.edu/exchange/waldron/organic

Worker in Protein Glucose Starch? Lipid? break Lunch/Snack ? ? Y/N Y/N Y/N room Y/N Jose Bean Burrito with Cheese Ashley Fat-Free Yogurt Toast with Peanut Butter Bruce and Jelly Kiara Pretzel Evidence ?

1. Complete the following table to summarize the evidence and your interpretation of the evidence.

Worker Did he/she How do you know? Describe the evidence that in Break take Jerrell’s supports your conclusion. Room iPod? Y/N

Ashley