Identification of Macromolecules

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Identification of Macromolecules

Introduction
The purpose of this lab is to test for the presence of macromolecules in various foods. Tests are performed to describe the basic structure of proteins, lipids, glycerides, and carbohydrates. We are to recognize the positives and negatives in these macromolecules. Also we are to identify the roles that proteins, lipids, minerals, vitamins, and carbohydrates play in the body’s construction and metabolism.

Procedure/ Results

5.1 Carbohydrate Test

1. Obtain five test tubes. Label each one
2. Use a graduated cylinder to transfer 2 mL of distilled water 3. Repeat step 2 with each of the food substances.
4. Add 10 drops of Benedict’s Solution to each test tube. 5. Gently shake the contents of each test tube.
6. Place the test tubes in the boiling water bath for 3 minutes. Remove the test tubes using test tube holders. 7. A rusty brown color in response to Benedict’s Solution indicates a large amount of simple sugars.

Table 5.1 Benedicts Test| Results: Positive results color change of red/orange for Carbohydrate| contents| Initial color| Color after heating| conclusion| Distilled water| blue| blue| neg|

glucose| blue| red| pos|
maltose| blue| red| pos|
lactose| blue| red| pos|
sucrose| blue| blue| neg|
starch| Cloudy blue| Cloudy blue| neg|
fructose| blue| orange| pos|
Lemon juice| Teal/blue-green| green| neg|
Orange juice| green| Creamy orange| pos|
Non-diet soda| blue| orange| pos|
Diet soda| blue| blue| neg|

5.2 Carbohydrate Test

1. Obtain five test tubes. Label each one
2. Use a graduated cylinder to transfer 5 mL of distilled water 3. Repeat step 2 with each of the food substances.
4. Add 5 drops of Iodine to each test tube.
5. Gently shake the contents of each test tube.
6. Iodine causes complex carbohydrates to turn dark blue or black

Table 5.2 Lugol’s Test| Results: Positive results color change of blue/black for Carbohydrate| contents| Initial color| Color after heating| conclusion| Distilled water| clear| yellow| neg|

glucose| clear| yellow| neg|
maltose| clear| Orangey yellow| neg|
lactose| clear| yellow| neg|
sucrose| clear| yellow| neg|
starch| cloudy| Blue/black| pos|
cream| white| Creamy yellow| neg|

5.3 Lipid Test

1. Obtain five test tubes. Label each one
2. Use a graduated cylinder to transfer 5 mL of distilled
3. Repeat step 2 with each of the food substances.
4. Add 5 drops of Sudan III stain to each test tube.
5. Gently shake the contents of each test tube.
6. Sudan III will dissolve in lipids and stain them red

5.3 lipids test w/ Sudan IV| Results: Positive results separation of layers for Lipids| contents| Observation after addition of Sudan IV| conclusion| Distilled water| Mixed together| neg|

Vegetable oil| 2 layers| Pos|
Hamburger juice| Mixed together| neg|
Onion juice| Mixed together| neg|
Soft drink (diet)| Mixed together| neg|
cream| 3 layers| Pos|

5.4 Protein Test

1. Obtain five test tubes. Label each one
2. Use a graduated cylinder to transfer 5 mL of distilled water into the test. 3. Repeat step 2 with each of the food substances
4. Add 5 drops of Biuret Reagent to each test tube.
5. Gently shake the contents of each test tube.
6. Biuret Reagent changes color from blue to violet in the presence of protein.

5.4 Protein w/ Biuret reagent| Results: Positive results color change to red for Proteins| contents| Color Reaction| conclusion|
Distilled water| Light blue| neg|
starch| Light blue| neg|
Egg albumin| red| pos|
glucose| Light blue| neg|
Soft drink| Light blue/clear| neg|

5.5 Unknown Substance

5.5 test for unknown food substance | Substance A unknown| Test for Carbohydrates| Test for Lipids| Test for Proteins| Benedicts| Lugol| Uncoated paper| Sudan IV|...
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