Lab 2 Proteins and Starches

Daniel Bergey

Lab 2: Proteins and Starches

Purpose
The purpose of lab 2 and both tests with proteins and starches is to determine which substance contains either protein or starch.

Hypothesis
Proteins: I predict that any substance I test that derives from a living organism is will test positive proteins. Any substance that isn’t from a living organism more than likely will test negative for proteins.

Starches: I predict that any substance that contains any level of glucose will test positive for starch.

Materials
Physical: None

Virtual:
1. Test Tube Rack
2. 4-5 Test Tubes
3. Transfer Pipet
4. Protective Glasses
5. 3 Pieces of Paper Bag
6. DiWater
7. Evaporated Milk
8. 50% Egg White Solution
9. 1% Sucrose Solution
10. 1% Starch Solution
11. Onion Juice
12. 10% Sucrose Solution
13. Vegetable Oil
14. Biuret Reagent
15. Iodine
16. Benedicts Reagent

Methods
In this lab there are I complete two different tests. The procedure was relatively the same for each test. I would first add 3ml of a given substance to a test tube, followed by 5 drops of either Biuret Reagent or Iodine. Once the agent is added, I swirled the two substances and then observed the results. The first was to test proteins, and the second, was to test starches.

In the first test, Proteins, I used biuret reagent to determine which of the substances had protein. The substances I added biuret reagent to were, diwater, egg white solution, milk solution, and 1% sucrose solution. The procedures in which I took are the same ones listed above, using the biuret reagent.

In the second test, Starches, I used Iodine to determine which substance was starch and which wasn’t. The substances I added iodine to were, diwater, 1% starch solution, onion juice, and 1% sucrose solution. The procedures in which I took for the second test were the same ones as list in the first paragraph, using iodine.

Results
DiWater
Blue
50% Egg White Solution
Purple
Evaporated Milk
Purple
1% Sucrose Solution
Blue

Test 1: Proteins
Contents Results

Test 1: Starches
Contents Results
DiWater
Yellow
1% Starch Solution
Purple
Onion Juice
Yellow
1% Sucrose Solution
Yellow

Conclusion

Proteins:

Starches:

In both tests with the various substances my hypothesis was proven to be correct. I can conclude that if a substance derives from a living organism, it is more than likely to test positive for protein. While if a substance contains any level of glucose, in is more than likely to test positive as a starch.