Macromolecules of Life

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Macromolecules of Life
Exercise 1: Testing for Proteins
In this experiment Biuret Color is added to four substances, egg white, pepsin, sugar, and distilled water to test the detection of protein in each substance.
Substance Tested
Predicted Results
Biuret Color & Number of drops added
1. Egg White
Change color
5 drops –turned a yellow/light brown
2. Pepsin
Change color
5 drops- turned purple
3. Sugar
No Change
5 drops-no change in color
4. Distilled Water
No Change
5 drops-no change in color

The positive tubes were the tubes with the egg white, pepsin, and sugar.
Protein was found in the first two substances.
Biuret reagent can be used in a real life situation to test the detection of protein in food.
The predicted results were the same as the results.
Exercise 2: Testing for Sugar
To add Benedict’s reagent to four substances, glucose, starch, onion juice, and distilled water, to test the detection of sugar in each.
Test Sample
Predicted Results
Benedict’s Results
1. Glucose
Change in color
Color changed to a dark red
2. Starch
Change in color
Color changed to a dark red
3. Onion Juice
Change in color
Color changed to a dark red
4. Distilled Water
No change
No change in color

The test tube with the Glucose, Starch, and onion juice were the positive controls. The test tube with the distilled water was the negative control.
The predicted results were the same as the results.
This experiment concluded that there is starch present in Glucose, Starch, and onion juice.
You could use Benedict’s reagent in real life to test urine for sugar.
Exercise 3: Testing for Starch
Using IKI reagent to test the detection of starch in an onion and a potato. This is done by adding a drop of IKI reagent to the potato and the onion and examining both of them under a microscope looking for cell presence.
I think that there is more starch in a potato than an onion.
The potato under the microscope (160m magnification) without IKI reagent

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