NAME: ______________________
BLOCK: _______
DATE:_______
Introduction:
Due to your excellent background in organic chemistry, you have
been hired by Dr. Oliver Border of the Lancaster County Medical
Examiners Office to clear up a situation. During some confusion
with previous laboratory technicians, samples of stomach
contents from 5 murder victims got mixed up! Since these
specimens will serve as evidence in pending murder trials it is
essential that this mistake be corrected. The only information that
you have about these murder victims is what their last meal was.
Hopefully your knowledge of organic chemistry will enable you to
fill in the gaps and you will be able to match different stomach
contents samples with their “owners”. You should follow the
procedures (found on pages 3 – 5) for identifying various organic
molecules including monosaccharides, starch, lipids, and
proteins. Information about the last meals of the 5 victims is on
the next page:
1
VICTIM
NAME OF
VICTIM
A
Wendell Sputz
B
Margaret Little
C
U. R. Downs
D
Lucy
Wunderchomper
E
Davis O’Leary
LAST MEAL
A bag of jelly
beans and a
baked potato
A bag of
Skittles and tea
with honey
Spaghetti with
tomato sauce
A Big Mac
Value Meal
supersized with
an extra order
of supersized
fries and a
shake
A very lean filet
mignon and a
glass of mineral
water
2
BIOLOGICAL
MOLECULES
PROBABLY
IN THE
FOOD
OBJECTIVE:
The confused stomach contents have already been labeled 1-5.
You need to figure out which ones match Victims A-E.
1. Set up the experiment to test all five stomach contents at the
same time using the same test. For example fill Test Tube
#1 with some of stomach contents from Bottle #1.
2. Repeat this through Test Tube #5 which you’ll fill with some
of the stomach contents from Bottle #5.
3. Perform the same test on all 5 tubes. See the next few
pages for directions for testing each of the biological
molecules.
4. Record your results in Table 3-1 and analyze your results to
determine which stomach contents belong to which murder
victims. Think Put your conclusions in Table 3-2. GOOD
LUCK!
3
MATERIALS
Safety goggles
Five test tubes numbered 1-5
Test tube rack
Wire test tube holder
Benedict's solution
Iodine solution
Disposable pipettes numbered 1-5
Biuret's solution
Brown bag paper or paper towel
Graphite or Wax pencil
Hot plate with hot water bath
Test tube brush
Soapy water for clean up
Stomach contents of 5 victims
FOR ALL TESTING PROCEDURES
MAKE SURE YOUR SAFETY GLASSES ARE ON!
DIRECTIONS FOR LIPIDS TESTING
Brown Paper Test
1. Take a piece of brown bag paper and using a pencil to
divide it into 5 sections.
2. Label each section with the number of the stomach
contents.
3. Place 1-2 drops of each sample in the appropriate
section.
CAREFUL: Do not overdo the amount of food that you
put on the paper.
4. Set the paper aside until the end of the period, or even
the next day. This must dry completely to get accurate
results.
4
5. ANALYSIS: When dry hold the paper up to the light
and look for translucence. Any section that has light
coming through is positive for lipids.
DIRECTIONS FOR CARBOHYDRATES TESTING
Monosaccharide Testing
1. Fill the appropriately labeled test tube with 1-2 cm of
each of stomach contents.
2. Place 20 drops of the Benedict's solution in each test
tube.
3. Mix gently by swirling the test tube.
CAUTION: Benedicts is poisonous! If you get
Benedict’s solution on your skin then wash it off
immediately with soapy water. Clean up any spills on
lab top with soapy water.
4. Place the test tubes in the hot water bath and heat for
up to 5 minutes.
5. Remove the test tubes with a test tube holder after
changes have occurred and place in the test tube rack
until results are recorded.
CAREFUL: Tubes are hot!
5
6. ANALYSIS: Benedict's solution turns from clear blue to
a cloudy orange/red in the presence of a
monosaccharide. Varying colors of a cloudy green and
yellowish green indicate some simple sugar is present
and should be recorded as positive.
7. Record results in the data table.
8. Clean the test tubes using a test tube brush and soapy
water. Rinse well.
Starch Testing
1. Place 1-2 cm of each stomach contents into 5 correctly
labeled test tubes.
2. Place 3-5 drops of iodine solution into each test tube.
3. ANALYSIS: The iodine solution will change from brown
to a dark purple/black color in the presence of starch.
IODINE IS ALSO POISONOUS! DON’T GET IT INTO
YOUR EYES OR MOUTH.
4. Record the results in the data table.
5. Clean the test tubes using a test tube brush and soapy
water. Rinse well.
6
DIRECTIONS FOR PROTEIN TESTING
1. Place 1-2 cm of each stomach contents in the
appropriately labeled test tube (1-5).
2. Add 5-7 drops of biuret solution into each test tube.
BUIRET REAGENT IS VERY POISONOUS IF YOU
INGEST IT OR GET IT INTO YOUR EYES. ALSO KEEP IT
OFF YOUR SKIN BECAUSE IT CAN BURN YOUR SKIN.
3. ANALYSIS: Look for a color change. A positive result
for protein will be a pink-purple color.
4. Record results in the data table.
5. Clean the test tubes with the brush and soapy water.
Rinse well.
7
RESULTS
TEST
BIOLOGICAL
MOLECULE
Brown
Paper
TABLE 3-1
Stomach Stomach Stomach Stomach Stomach
Contents Contents Contents Contents Contents
1
2
3
4
5
Lipids
Benedict’s Monosaccharide
Iodine
Starch
Biuret
Protein
TABLE 3-2
VICTIM
NAME OF VICTIM
A
Wendell Sputz
B
Margaret Little
C
U. R. Downs
D
Lucy
Wunderchomper
E
Davis O’Leary
LAST MEAL
A bag of jelly
beans and a
baked potato
A bag of
Skittles and tea
with honey
Spaghetti with
tomato sauce
A Big Mac
Value Meal
supersized with
an extra order
of supersized
fries and a
shake
A very lean filet
mignon and a
glass of mineral
water
8
NUMBER OF
STOMACH
CONTENTS
THAT MATCHES
CONCLUSIONS
Instructions:
On a separate sheet of paper, write a BUSINESS STYLE
LETTER to Dr. Oliver Border analyzing your data and
stating your conclusions. Your letter must be typed! Use
the business letter macro that is available through the MS
Word “NEW” document menu. Include the following in your
letter.
1. A fake business name and a logo for your business.
Use your real name in the letter so that I can give you
credit for the assignement.
2. Describe why you were hired, what you did, and what
you discovered. Explain how you came to the
conclusions that you did based on the tests that you
did.
3. Also include if and where any errors in procedure may
have caused the information that you collected to be
even slightly unreliable.
4. State any changes in procedure that you think will help
the investigation to run more smoothly in the future.
5. Lastly, attach the results page from the lab to your
letter.
9