Organic Molecules
Cells contain many organic molecules. These molecules are essential to life. Many of them
are acquired from the food we eat. In this lab you will study carbohydrates, proteins and
fats.
Procedure:
Follow the directions below that use the web site: Biology Labs Online…..Dennis
Anderson, Professor of Biology
The URL is:
http://www.occc.edu/biologylabs/index.htm
Once here, select Organic molecules from the left hand menu..then begin with Carbs!!
□ Monosaccharides are simple sugars that react with a mixture
called _____________________ or __________________. The
reaction changes the color of the reagent to green, red or orange
depending oh how much sugar is present. Benedict's reagent can
be used to test for the presence of many of the simple sugars.
□ Complete the experiment that follows with Benedict's reagent. Be
sure to include any information requested!
List the steps that are followed to test for monosaccharides:
1.
2.
3.
Color of the solution in test tube_____________________________
Then add glucose solution to the test tube…boil again….and then
record the color of the test tube_____________________________
Continue….and you will see two test tubes in boiling water. Complete
the chart below for the tubes…
Tube color
Sugars present (+/-)
Continue…yet again…..and record the color of the tube when you add
iodine to water________________________
Record the color of the tube when you add iodine to
starch__________________________
Which of the tubes to the right is a
positive test for starch and which is
a negative? Label each tube
correctly!!
Now move on to proteins….
Proteins react with _________________ reagent. The reaction turns the
color of biuret from a _____________________ to
______________________.
Complete the experiment that follows with biuret reagent….
List the steps that are followed to test for a protein
1.
2.
Record the color of the solution of biuret and water_________________
Is this a positive or negative test for protein?__________
Record the color of the solution when the protein solution is added with
the water and the biuret_______________ Is this a positive or negative
test?________________
Below are two tubes with biuret reagent. Which one is positive for protein
and which is negative? Label each tube correctly!!
Now on to fats….
________________ is a dye that will dissolve in fats. It will not dissolve
in carbohydrates or proteins. Sudan IV will change the color of a fat to
______________.
Complete the experiment that follows with Sudan IV.
Record the color of the solution of Sudan IV and
water______________Is this a positive or negative test result?_________
Record the color of the test tube with Sudan IV and vegetable
oil________________ Is this a positive or negative test result?_________
Now to continue…choose foods. Complete all the tests for all six of the
foods! Complete the chart below:
Simple sugars
Color
+/-
Starches
Color
+/-
Fats
Color
+/-
Proteins
Color
+/-
Potato
Juice
Almonds
Eggs
Pink
salmon
Whole
milk
Conclusion Paragraph
□ In this paragraph include the following…
o A summary of the positive test results seen for simple sugars,
starches, fats and proteins
o A summary of each of the foods tested(in the chart above) in terms
of their content of simple sugars, starches, fats and proteins