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:

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

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 Starches Fats Proteins

Color / +/- / Color / +/- / Color / +/- / 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

Organic Molecules