Download Ch 3 Macromolecule Lab

Macromolecules in Food Lab Honors Living Environment Introduction: ​
Biological macromolecules are defined as large molecules made up of smaller organic molecules. There are four classes of macromolecules: carbohydrates, lipids, proteins and nucleic acids. Carbohydrates consist of two major groups, sugars and starches, and are a great source of energy. Lipids are hydrophobic molecules which also store energy and consist of fats, waxes, and oils. All living things make and depend upon proteins, which are made up of repeating amino acid units. DNA and RNA are both nucleic acids, used for storing and communicating genetic information. Purpose: ​
To investigate three of the biological macromolecules by testing for the presence of starches (carbohydrate), proteins, and lipids in foods. This will be done using three separate tests,​
but YOU will be responsible for determining what macromolecule each substance is testing for. 1. Hypothesis: Which of the eight substances do you think will test positive for PROTEIN? 2. Hypothesis: Which of the eight substances do you think will test positive for LIPIDS? 3. Hypothesis: Which of the eight substances do you think will test positive for CARBOHYDRATES? The eight substances under investigation are: water, protein powder solution, potato solution, vegetable oil, corn starch solution, apple juice, egg white solution, glycerin. Procedures: Test #1 – Biuret Indicator: 1) CAUTION: Biuret solution can burn skin. Wear gloves and goggles! Be sure to wipe off and wash off any spills with plenty of water. 2) Fill 8 wells of your first well plate half full with the Biuret indicator. 3) Fill 8 wells of your second well plate with the liquid solutions you will be testing. 4) Using a clean pipet, add 3­5 drops of the indicator from the first well plate to each of the eight liquid solutions in the second well plate. 5) Observe and record the observations. 6) **Positive test will be purple; a negative test will be blue** 7) Clean out your well plate by rinsing it off at the sink. Test #2 – “Grease Spot” Test: 1) Obtain a long strip of a brown paper bag. Make sure it is not doubled up. 2) Use a pen to label where you will place one drop of each liquid solution. 3) Using the pipet, place one large drop of the liquid solution over the appropriate word. DO NOT MIX PIPETS! 4) Let the solutions sit for one minute. 5) Take the paper bag and hold it up to the light or window. 6) Observe and record the observations in your data table using either a + or a – sign . 7) **Positive test will be a translucent (see through) “grease spot”** Test # 3 – Iodine Indicator: 1) CAUTION: Iodine can burn skin. Wear gloves and goggles. Be sure to wipe off and wash off any spills with plenty of water. 2) Fill 8 wells of your first well plate half full with the Iodine indicator. 3) Fill 8 wells of your second well plate with the liquid solutions you will be testing. 4) Using a clean pipet, add 3­5 drops of the indicator from the first well plate to each of the eight liquid solutions in the second well plate. 5) Observe and record the observations. 6) **Positive test will be a very dark purple/black; a negative test will be brownish orange** 7) Clean out your well plate by rinsing it off at the sink. Questions for Interpretation of Results: 1. Define the term macromolecule. 2. What are the four biological macromolecules? 3. According to your results, Biuret solution is an indicator for which macromolecule (Carbohydrates, Proteins or Lipids)? 4. According to your data, the “grease spot” test indicates the presence of which macromolecule (Carbohydrates, Proteins or Lipids)? 5. According to your data, Iodine is an indicator for what macromolecule (Carbohydrates, Proteins or Lipids)?