You Are What You Eat: An
Investigation of Macromolecules
Teacher Materials
Learning Goals, Objectives, and Skills ............................................................................. 2
Standards Alignments..................................................................................................... 3
Laboratory Set-Up Manual ............................................................................................. 5
Instructor Laboratory Guide ........................................................................................... 7
Answers to Student Questions ....................................................................................... 8
Post-Lab Extension Activities .......................................................................................... 9
*Please consider adapting this lab to include some student-centered investigation. Some suggestions, ideas,
and tips can be found in a separate document called "Student-Centered Investigation"
1
You Are What You Eat: An Investigation of Macromolecules
Learning Goals, Objectives, and Skills
Student Learning Goals:

Students will understand the basic structures and functions of the four classes of macromolecules.

Students will understand that most macromolecules are polymers.

Students will understand how hydrolysis and dehydration synthesis reactions relate to macromolecules.

Students will understand that nearly all food is derived from organisms, and therefore is made up of cells.

Students will understand that cells contain carbohydrates, lipids, nucleic acids, and proteins.

Students will understand that the presence of macromolecules in cells can be detected with simple chemical
tests.
Student Learning Objectives:

Students will predict the presence of macromolecules in lima beans and corn seeds.

Students will relate the cycling of nutrients in the biosphere to the cycling of nutrients within organisms as
macromolecules are broken down and synthesized.

Students will prepare positive and negative controls for the tests that determine the presence of each of four
macromolecules in two different solutions.

Students will test for the presence of macromolecules in lima beans and corn seeds.
Scientific Inquiry Skills:

Students will design and conduct scientific investigations.

Students will make measurements and record data.

Students will compare their results to those of the control and to their predictions.

Students will follow laboratory safety rules and regulations.
Laboratory Technical Skills:

Students will demonstrate proper use of micropipettors.
2
You Are What You Eat: An Investigation of Macromolecules
Standards Alignments
MA Science and Technology/Engineering Curriculum Framework (2006)
Biology
1.1 Recognize that biological organisms are composed primarily of very few elements. The six most common are C, H,
N, O, P, S.
1.2 Describe the basic molecular structures and primary functions of the four major categories of organic
1.3 Explain the role of enzymes as catalysts that lower the activation energy of biochemical reactions. Identify factors,
such as pH and temperature, which have an effect on enzymes
Scientific Inquiry Skills

SIS1. Make observations, raise questions, and formulate hypotheses.

SIS2. Design and conduct scientific investigations.

SIS3. Analyze and interpret results of scientific investigations.

SIS4. Communicate and apply the results of scientific investigations.
DRAFT REVISED MA Science and Technology/Engineering Standards (2013)
*Please note that these are DRAFT standards that have not yet been submitted for formal review or adoption.
Biology
HS-LS1-1. Explain that genes are regions in the DNA that code for proteins, which carry out the essential functions of
life. Construct a model of transcription and translation to explain the roles of DNA and RNA in coding the instructions
for polypeptides, which make up proteins. Explain that different classes of proteins regulate and carry out the
essential functions of life.
[Clarification Statement: Four classes of proteins that regulate and carry out the essential functions of life include: enzymes (speeding up chemical
reactions), structural proteins (providing structure and enabling movement), hormones (sending signals between cells), and antibodies (fighting
disease).]
[Assessment Boundary: Assessment does not include specific names of proteins or rote memorization of steps of transcription and translation.]
HS-LS1-6. Construct and revise an explanation based on evidence that macromolecules are primarily composed of six
elements, where carbon, hydrogen, and oxygen atoms from carbohydrates may combine with nitrogen, sulfur, and
phosphorus to form large carbon-based molecules.
[Clarification Statement: Large carbon-based molecules included are proteins, carbohydrates, amino acids, nucleic acids, and lipids.]
[Assessment Boundary: Assessment does not include the details of the specific chemical reactions or identification of specific macromolecules.]
NRC Practices







Asking questions and defining problems
Planning and carrying out investigations
Analyzing data
Mathematical and computational thinking
Constructing explanations and designing solutions
Engaging in argument from evidence
Obtaining, evaluating, and communicating information
3
You Are What You Eat: An Investigation of Macromolecules
Laboratory Set-up Manual
Supply List:
For lab preparation:














30 x lima beans (Johnny’s Seeds #049.36)
60 x corn seeds (Johnny’s Seeds #267.53)
potting soil
small flower pots or plastic cups
small dropper bottles (plastic or glass), 2 per group minimum
small light-blocking glass bottles, 1 per group minimum
microcentrifuge tubes, 4 per group minimum
immersible blender
2 x 600-mL plastic beaker or quart deli container
large coffee filters (at least two)
bottles for seed solutions and water
dH2O
Hot plate or microwave
600 ml glass beaker (for heating water)
For each group:





















5 mL Biuret solution (Fisher #S25200B)
5 mL Benedict’s Solution (Fisher #S25193A)
5 mL Lugol’s solution (Fisher #S75041)
100 µL of SYBR Safe solution
1 mL Sudan IV
bottle of corn solution (15 mL)
bottle of lima bean solution (15 mL)
1  p200 micropipettor and pipette tips
2  microcentrifuge tubes
8  test tubes
1  test tube rack
4–10  transfer pipettes
permanent marker (such as Sharpie)
transfer pipettes
50 uL 500 ug/mL lambda DNA (NEB #N3011S)
2 mL vegetable oil
2 mL 2 mg/mL BSA solution
2 mL 5 % starch solution
2 mL glucose solution
dH2O
3 mL ethanol
Lab Set-up Calendar:
2 weeks before lab:
 Check supplies and order any needed materials.
4
 If making any substitutions to the supply list, edit the student protocol accordingly.
 Plant corn seeds and lima beans. This can be done as a demonstration or students can plant their own seeds.
1-2 days before lab:
 Dispense indicator solutions into bottles for each lab bench. Important! The set up is based on 15 groups, each
with their own set of indicators. If you are letting groups share bottles or if bottles will be used for several classes you
will need to adjust the volumes accordingly.
1.
Aliquot 5 mL Biuret solution into small dropper bottles (plastic or glass).
2.
Aliquot 5 mL Benedicts solution into small dropper bottles (plastic or glass).
3.
Aliquot 5 mL Lugol’s solution into small containers, preferably glass and light-blocking.
4.
Dilute SYBR Safe by adding 80 µL of 10,000 X SYBR Safe to 1420 µL of dH20. Dispense 100µL into 15
microcentrifuge tubes. Save extra for lab day. The tubes should be stored in the dark until used.
 Put lima beans and corn seeds in separate cups with water. The seeds will imbibe water so there needs to be four times
as much water as seeds. *MUST BE DONE AT LEAST 15 HOURS BEFORE LAB* Timing is critical for this step—it takes as
least 15 hours for the seeds to get soft enough to use. If you need to
1 day before lab:
 Prepare SYBR Safe dilution
1.
2.
3.
4.
Add 1980 µL sterile dH2O to a 15-mL conical tube.
Add 20 µL SYBR Safe and swirl to mix.
Aliquot 100 µL into microcentrifuge tubes, one per lab group
Store in dark until use.
 Set up student lab stations with all durable materials.
Morning of lab:
 Prepare seed “solutions”
1.
2.
3.
4.
5.
6.
7.
8.
9.
Add approximately 25 soaked lima beans and 50 mL dH2O to a 600-mL plastic beaker or quart deli
container.
Using an immersion blender, coarsely chop the seeds into 3–6 mm pieces. Important! Do not “over
chop.” You do not want a puree! A few quick pulses with the blender should create a suspension with
pieces about 3–6 mm, and some larger pieces are fine.
Add an additional 200 mL H2O.
Stir vigorously.
Filter out the large chunks using the coffee filter.
Aliquot 15 mL of solution into student bottles
Refrigerate until use
Repeat steps 1–7 using 60 soaked corn seeds.
Save some of the pieces of the lima beans for the students to use to test for starch.
 Prepare starch solution
1.
Add 5 g of corn starch to 100 mL of water and mix well. An alternative method is to use spray starch—squirt
enough starch into the water until it turns “milky.” Test with iodine to make sure it is concentrated enough.
 Set up boiling water bath for Benedict’s test or make microwave available
As students start the pre-lab activity:
 Display corn and lima bean seedlings.
5
You Are What You Eat: An Investigation of Macromolecules
Instructor Laboratory Guide
Laboratory Procedure Tips:
1.
The seeds should germinate in 7–10 days but allow more time if your room is below 68F or gets very cool at
night. Depending on the growth desired, plant seeds up to three weeks ahead
2.
The seeds will grow faster if they are soaked in water for 24 hours prior to planting.
3.
A spiral fluorescent bulb can be used for light if you do not have a sunny window. By using a curtain of foil to
increase the light, growth rate can be accelerated.
4.
The starch test on the lima bean works better if the students just put a drop of Lugol’s solution on a piece of
the seed rather than using the suspension.
5.
The control standards are available as a jpeg file if you have time and/or facilities constraints and want to
provide controls for the students.
6
You Are What You Eat: An Investigation of Macromolecules
Answers to Student Questions
Protocol-Embedded:
p. 4, tuna fish and strawberries

Protein, carbohydrates, lipids, and nucleic acids all contain carbon.

Proteins contain nitrogen.

Nucleic acids contain phosphorus.

Because they are made up of different types of cells.
p. 4, plants and macromolecules: Glucose, C6H12O6; cellular respiration
p. 4, galactose: C6H12O6; It is the same
p. 5, enzymes: They lower the activation energy required for reactions OR they speed up the rates of chemical
reactions.
P. 5, diagram: it’s RNA because it contains uracil.
P. 5, oil and water: They don’t mix because oil is a lipid and lipids are hydrophobic, which means that they do not
dissolve in water.
Pre-Lab:
1.
2.
4.
carbohydrates, proteins, lipids, and nucleic acids
omelet with black beans and cheese—all of these foods are good sources of protein. Bread is primarily a
carbohydrate, butter is primarily a lipid, and jam is primarily made up of carbohydrates.
Plants are called “producers” because they can produce their own carbohydrates via photosynthesis.
Consumers have to consume food from the environment to produce carbohydrates.
carbohydrates, monosaccharides and a disaccharide; hydrolysis (water is released)
5.
1–a; 2–e; 3–b; 4–c; 5–d.
3.
Post-Lab and Analysis:
1.
2.
3.
Answer will vary.
Most likely this label is from a can of corn. The sugar and fat content is more consistent with corn than lima
beans
Strawberries are made up of cells, and all cells are surrounded by a phospholipid bilayer (cell membrane). So,
strawberries definitely contain lipids!
7
You Are What You Eat: An Investigation of Macromolecules
Post-Lab Extension Activities
Student Oral Presentation:
Students can report the findings of their student-centered investigations to the class using a PowerPoint presentation
that includes the following information:





Experimental question—what you hope to learn from performing the experiment.
Hypothesis—a testable, proposed answer to the experimental question based on prior knowledge.
Experimental system and data collection methods—flowchart of how the experiment was performed and
how data was collected. This should NOT include a detailed summary.
Results—observations, data tables, figures, etc.
Conclusions—should the hypothesis be accepted or rejected as supported by key data.
Online resource for effective PowerPoint presentations:
http://office.microsoft.com/en-us/powerpoint-help/tips-for-creating-and-delivering-an-effectivepresentation-HA010207864.aspx
Student Lab Report:
Students can report the findings of their student-centered investigations through a written lab report. Your school
may have its own lab report format, but generally lab reports include the following information:






Title—brief summary reflecting the factual content of the investigation.
Introduction—includes questions being answered, hypothesis and background information.
Materials—list of supplies needed to perform the lab.
Procedure—step-by-step procedure (with enough detail so someone could repeat the experiment).
Results—observations, data tables, figures, etc. and a brief narrative summary of results.
Conclusion—explanation supported by evidence for whether the hypothesis should be accepted or rejected.
Online resources for writing lab reports:
http://www.mhhe.com/biosci/genbio/maderinquiry/writing.html
http://www.ncsu.edu/labwrite/
Student Writing Exercise:
Ask students to read a current newspaper or journal article related to GMO foods and write a paragraph answering a
series of prompts. For example, students could read the online article The Truth About Genetically Modified Foods
(http://www.scientificamerican.com/article/the-truth-about-genetically-modified-food/) and write a brief paragraph
outlining the pros and cons of GMO foods.
8
Websites:
http://concord.org/stem-resources/tree-life
Videos:
www.youtube.com/watch?v=nvMxIEgbsIo
https://www.youtube.com/watch?v=PYH63o10iTE
https://www.youtube.com/watch?v=QWf2jcznLsY
Games:
Related Experiments:
http://www.seplessons.org/node/362
http://faculty.uncfsu.edu/jraynor/BIOL%20200%20Online%20Lab/Biological%20Molecules%20Lab.htm
9