Biological Biological MacromoleculesMacromolecules

An Inquiry Investigation Into An Inquiry Investigation Into the Properties of Certain the Properties of Certain Foods…..Foods…..

Purpose:Purpose:

To determine which biological To determine which biological macromolecules are found within macromolecules are found within each of the following foods:each of the following foods:– PeanutsPeanuts– CrackersCrackers– EggsEggs– MilkMilk

Your Goal:Your Goal: To design a set of experiments that To design a set of experiments that

will illustrate which biological will illustrate which biological macromolecules are present in each of macromolecules are present in each of the foods previously listed.the foods previously listed.

You must include the following You must include the following sections in your lab write up:sections in your lab write up:– TitleTitle– PurposePurpose– ApparatusApparatus– Procedure (for each of the 4 tests)Procedure (for each of the 4 tests)– DataData– Results & Error AnalysisResults & Error Analysis– ConclusionConclusion

Questions to think Questions to think about:about: Which macromolecules do you think are Which macromolecules do you think are

present in each of the foods listed?present in each of the foods listed? What kinds of data will you collect?What kinds of data will you collect? What are your variables?What are your variables? What is your control?What is your control? Can each food have more than one type Can each food have more than one type

of macromolecule? How will you know?of macromolecule? How will you know? How will you convey your results to the How will you convey your results to the

reader?reader?

Testing for Simple Testing for Simple Sugars:Sugars:

Benedict’s TestBenedict’s Test: In the presence : In the presence of monosaccharides, a positive of monosaccharides, a positive test results in a yellow-orange test results in a yellow-orange colored solution.colored solution.– MUST be heated to activate the test!MUST be heated to activate the test!– ONLY tests for simple sugars; no ONLY tests for simple sugars; no

positive tests for polysaccharides.positive tests for polysaccharides.

Testing for Starch Testing for Starch (Polysaccharides):(Polysaccharides):

Starch TestStarch Test: In the presence of : In the presence of starch, a positive test results in starch, a positive test results in the Iodine solution turning a deep the Iodine solution turning a deep blue-black color.blue-black color.– Does NOT need to be heated.Does NOT need to be heated.

Testing for Lipids:Testing for Lipids:

Sudan IV TestSudan IV Test: In the presence : In the presence of lipids, this compound will stain of lipids, this compound will stain the long hydrocarbon chains of the long hydrocarbon chains of fatty acids a red-orange color.fatty acids a red-orange color.– Must dissolve the lipids in ethanol Must dissolve the lipids in ethanol

(alcohol) first (non-water soluble).(alcohol) first (non-water soluble).– No heat necessary.No heat necessary.

Testing for Proteins:Testing for Proteins:

Biuret TestBiuret Test: In the presence of a : In the presence of a protein, this solution will produce protein, this solution will produce a violet colored solution.a violet colored solution.– Must mix well (shake vigorously)Must mix well (shake vigorously)– Allow solutions to sit for at least 5 Allow solutions to sit for at least 5

minutes BEFORE establishing if minutes BEFORE establishing if there has been a reaction or not.there has been a reaction or not.

What Materials Can What Materials Can You Use?You Use?

The following is a list of materials The following is a list of materials available to you:available to you:– Test tubesTest tubes– The 4 test solutions previously discussedThe 4 test solutions previously discussed– Ethanol Ethanol – Alcohol burnersAlcohol burners– Saliva (hint, hint…..!)Saliva (hint, hint…..!)– Beakers, graduated cylinders, and/or Beakers, graduated cylinders, and/or

flasksflasks– Anything else you can convince me you Anything else you can convince me you

might need…..!might need…..!

What’s next?What’s next?

You have the rest of this class, plus the You have the rest of this class, plus the next period, to design and conduct your next period, to design and conduct your experiment. experiment.

You need my approval to move from the You need my approval to move from the design phase to actual testing.design phase to actual testing.

EVERYTHINGEVERYTHING will be written up in you will be written up in you lab notebook.lab notebook.

Use the Use the AP Bio Lab RubricAP Bio Lab Rubric to help guide to help guide your official write up.your official write up.

Make sure to answer all of the following Make sure to answer all of the following questions in your conclusion when questions in your conclusion when finished.finished.

Questions to answer:Questions to answer:

1.1. Summarize your experiment.Summarize your experiment.2.2. Were some of your initial assumptions Were some of your initial assumptions

as to which type of molecule was in as to which type of molecule was in each food confirmed or denied? each food confirmed or denied? Explain.Explain.

3.3. How did you test each compound for How did you test each compound for simple and/or complex sugars? simple and/or complex sugars? Explain.Explain.

4.4. Describe the purpose of having a Describe the purpose of having a control for each test.control for each test.

5.5. What might have been some sources of What might have been some sources of error during your experimentation? error during your experimentation? Explain.Explain.