McMush Lab: Which Organic Molecules are in Our Food
(as always, all sections in bold must be recorded in science journal, as well as date and partners)
Purpose: To chemically identify organic molecules present in our food and trace their
origins
Materials: “McMush”, beakers, graduated cylinder, test tubes, test tube clamp, hot plate,
Benedict’s Soln., Biuret Soln., Lugol’s iodine soln., Sudan III soln., 1% silver nitrate
soln., blender
Procedure: (summarize each test by making flow chart diagram… see example on board)
Part I. Testing for Known Substances: What does a positive result look like? (be
certain all test tubes are absolutely clean!)
A. Protein Test: Place 5 ml of the gelatin solution into your test tube and 5 ml of your
negative control (distilled water) into a different test tube. Add ten drops of Biuret
Solution to each tube. Record the response for the positive protein and for a negative
response (control). Clean equipment
B. Carbohydrate Test
1. Glucose Test: Place 5 ml of the glucose solution into your test tube and add
10 drops of Benedicts Solution. Do the same for the negative control
(distilled water). Place the tube in a beaker of boiling distilled water and
boil for five minutes. USE TEST TUBE CLAMPS TO HOLD HOT TEST
TUBES. Record the response for the positive glucose and for a negative
response (control). Clean equipment
2. Starch Test: Place 5 ml of the starch solution into your test tube and 5 ml
of your negative control (distilled water). Add 5 drops of Lugol’s iodine
solution. Record the response for the positive starch and for a negative
response (control). Clean equipment
C.
Lipids Test: Place 5 ml of the lipid solution into your test tube and 5 ml of your
negative control (distilled water into a different test tube. Add 5 drops of Sudan III
stain. Gently mix the contents by covering with parafilm and slowly inverting 5
times. Record the response for the positive lipid and for a negative response
(control). Clean equipment
D. Minerals and Vitamin Test
1. Chloride Test: Place 5 ml of the salt solution into your test tube and do the
same for the negative control (distilled water). Add 5 drops of silver nitrate
solution. Record the response for the positive chloride and for a negative
response (control). Clean equipment
McMush Lab: Which Organic Molecules are in Our Food
(as always, all sections in bold must be recorded in science journal, as well as date and partners)
Purpose: To chemically identify organic molecules present in our food and trace their
origins
Materials: “McMush”, beakers, graduated cylinder, test tubes, test tube clamp, hot plate,
Benedict’s Soln., Biuret Soln., Lugol’s iodine soln., Sudan III soln., 1% silver nitrate
soln., blender
Procedure: (summarize each test by making flow chart diagram… see example on board)
Part I. Testing for Known Substances: What does a positive result look like? (be
certain all test tubes are absolutely clean!)
A. Protein Test: Place 5 ml of the gelatin solution into your test tube and 5 ml of your
negative control (distilled water) into a different test tube. Add ten drops of Biuret
Solution to each tube. Record the response for the positive protein and for a negative
response (control). Clean equipment
B. Carbohydrate Test
1. Glucose Test: Place 5 ml of the glucose solution into your test tube and
add 10 drops of Benedicts Solution. Do the same for the negative
control (distilled water). Place the tube in a beaker of boiling distilled
water and boil for five minutes. USE TEST TUBE CLAMPS TO
HOLD HOT TEST TUBES. Record the response for the positive
glucose and for a negative response (control). Clean equipment
2. Starch Test: Place 5 ml of the starch solution into your test tube and 5
ml of your negative control (distilled water). Add 5 drops of Lugol’s
iodine solution. Record the response for the positive starch and for a
negative response (control). Clean equipment
C.
Lipids Test: Place 5 ml of the lipid solution into your test tube and 5 ml of your
negative control (distilled water into a different test tube. Add 5 drops of Sudan III
stain. Gently mix the contents by covering with parafilm and slowly inverting 5
times. Record the response for the positive lipid and for a negative response
(control). Clean equipment
D. Minerals and Vitamin Test
1. Chloride Test: Place 5 ml of the salt solution into your test tube and do
the same for the negative control (distilled water). Add 5 drops of
silver nitrate solution. Record the response for the positive chloride and
for a negative response (control). Clean equipment
Data Part 1 Test of Known Substance
Organic Molecule (Food)
Reagent Test
A.
Protein (gelatin)
Biuret Solution
Results
(record what it looks like)
(+)
A.
Protein Negative Control
Biuret Solution
(-)
B1. Simple Carbohydrate
(glucose)
Benedicts Solution
(+)
B1. Simple Carb Negative
Control
Benedicts Soluton
(-)
B2. Complex Carbohydrate
(starch)
Lugol’s Iodine
(+)
B2. Complex Carb Negative
Control
Lugol’s Iodine
(-)
C. Lipids Test (oil)
Sudan III Stain
(+)
C. Lipids Negative Control
Sudan III Stain
(-)
D1. Chloride Test (NaCl salt)
Silver Nitrate
(+)
D1. Chloride Negative Control
Silver Nitrate
(-)
D2. Vitamin C
Indophenol Solution
(+)
D2. Vitamin C Negative Control
Indophenol Solution
(-)
Data Part II McMush - Our Sample: ____________________________
Organic
Reagent Test
Prediction
Result
Result
(+ or -)
Molecule
Description
Protein
Biuret
Simple
Carb
(sugar)
Complex
Carb
Benedict’s
Solution
Lipid (fats
and oils)
Sudan III
Salt (NaCl)
Silver Nitrate
Vitamin C
Indophenol
Solution
Main Use in the
Body
Lugol’s
Iodine
Example:Ion charge
helps our electrical
nervous system.
Data Part I Test of Known Substance
Organic Molecule (Food)
Reagent Test
A.
Protein (gelatin)
Biuret Solution
Results
(record what it looks like)
(+)
A.
Protein Negative Control
Biuret Solution
(-)
B1. Simple Carbohydrate
(glucose)
Benedicts Solution
(+)
B1. Simple Carb Negative
Control
Benedicts Soluton
(-)
B2. Complex Carbohydrate
(starch)
Lugol’s Iodine
(+)
B2. Complex Carb Negative
Control
Lugol’s Iodine
(-)
C. Lipids Test (oil)
Sudan III Stain
(+)
C. Lipids Negative Control
Sudan III Stain
(-)
D1. Chloride Test (NaCl salt)
Silver Nitrate
(+)
D1. Chloride Negative Control
Silver Nitrate
(-)
D2. Vitamin C
Indophenol Solution
(+)
D2. Vitamin C Negative Control
Indophenol Solution
(-)
Data Part II McMush –Our Sample ____________________________
Organic
Reagent Test
Prediction
Result
Result
(+ or -)
Molecule
Description
Protein
Biuret
Simple
Carb
(sugar)
Complex
Carb
Benedict’s
Solution
Lipid (fats
and oils)
Sudan III
Salt (NaCl)
Silver Nitrate
Vitamin C
Indophenol
Solution
Main Use in the
Body
Lugol’s
Iodine
Example:Ion charge
helps our electrical
nervous system
Data Part III Class Data:Tracing the Molecules McMush : We tested_____________
_____________________ ____________________________
Substance
Protein
Simple Complex
Lipids
Salt
Vitamin
(+ or -)
(+ or -)
(+ or -)
Carbs
Carbs (+
C
(+ or -)
or -)
(+ or -)
Meat and
Cheese
Bun
French
Fries
Drink
Apples
Analysis (answer these questions on the next page, NOT on this handout. Explain
thoroughly so I know you understand. Answers on this sheet will not be graded.)
1. Why did we use BOTH positive and negative controls in Part I (in other words,
what does each one tell you)?
2. Discuss how well your predictions in Part II worked. Be specific, meaning say
exactly which ones you were right about and which ones were wrong. Explain
why you think you were accurate or inaccurate.
3. Consider one carbon atom in the protein molecule of the hamburger. Where did
that carbon come from? And where was that carbon before that? And before
that? (in other words trace the pathway of that carbon atom.
4. Describe any sources of error in your lab. Include whether it should have made a
difference in your results and which way it would have done so (for example:
“We used only 3 ml of solution in our lab, but that should not change the results,
just make the color more intense.”)
Conclusion: (answer on the next page, NOT on this handout. Explain thoroughly so I
know you understand. Answers on this sheet will not be graded.)
Trace the pathway of each of the organic molecules in our lab back to their source
1. Carbohydrates in the buns and French fries
2. Glucose in the drink
3. Carbohydrates in the apples
4. Protein in the hamburger
5. Lipids in the French fries
Please do this with a labeled diagram and words to help explain.
Data Part III Class Data:Tracing the Molecules McMush : We tested_____________
_____________________ ____________________________
Substance
Protein
Simple Complex
Lipids
Salt
Vitamin
(+ or -)
(+ or -)
(+ or -)
Carbs
Carbs (+
C
(+ or -)
or -)
(+ or -)
Meat and
Cheese
Bun
French
Fries
Drink
Apples
Analysis (answer these questions on the next page, NOT on this handout. Explain
thoroughly so I know you understand. Answers on this sheet will not be graded.)
1. Why did we use BOTH positive and negative controls in Part I (in other words,
what does each one tell you)?
2. Discuss how well your predictions in Part II worked. Be specific, meaning say
exactly which ones you were right about and which ones were wrong. Explain
why you think you were accurate or inaccurate.
3. Consider one carbon atom in the protein molecule of the hamburger. Where did
that carbon come from? And where was that carbon before that? And before
that? (in other words trace the pathway of that carbon atom.
4. Describe any sources of error in your lab. Include whether it should have made a
difference in your results and which way it would have done so (for example:
“We used only 3 ml of solution in our lab, but that should not change the results,
just make the color more intense.”)
Conclusion: (answer on the next page, NOT on this handout. Explain thoroughly so I
know you understand. Answers on this sheet will not be graded.)
Trace the pathway of each of the organic molecules in our lab back to their source
1. Carbohydrates in the buns and French fries
2. Glucose in the drink
3. Carbohydrates in the apples
4. Protein in the hamburger
5. Lipids in the French fries
Please do this with a labeled diagram and words to help explain.