Lab 2- Biological Molecules
BIOL 1131, 34721
Ethan Little- 100559592
Professor Wilson
Date Preformed: Sept 17/14
Date Submitted: Sept 24/14
Objective
The objective in this lab is to test different biological molecules in a substance using a variety of
simple chemical tests. The tests will be used on known substances as confirmation of the validity of the
substance and then the tests will be performed on three unknown substances to identify the biological
macromolecules contained in the unknowns.
Rational
For each test performed, a positive test that indicates the presence of the molecule in a
particular substance gives a very different result than when the test is negative. For all the tests
performed a positive and negative control is used. A substance that is known to test positive in a
particular test demonstrates what a positive result looks like and vice versa with a negative one. This will
help distinguish a positive and negative result when testing the unknown.
Materials and Methods
Materials:
-
Test tubes
Distilled water
Onion
Bread
Butter
Fruit juice
Milk
Potato
Boiling chips
Marker
Brown paper
Vegetable oil
Tween
Reagents:
-
Safety
Iodine solution
Starch solution
Benedicts solution
Glucose solution
Protein source
Biuret solution
Chemical/Reagent
Iodine Solution
Hazards/Precautions
-hazardous is case of ingestion
-slightly hazardous in skin contact
-can be toxic
SAFTEY MEASURES
-eye contact: flush for 15min
-skin contact: wash with soap & water and get
medical attention if irritation follows
-inhalation: get fresh air
-hazardous is eye contact
-hazardous in skin contact
SAFTEY MEASURES
-eye contact: flush eyes with water for 15 min.
-skin contact: wash with soap & water
-inhalation: get fresh air
*if problems ensue after this seek medical
attention
-very hazardous in skin contact and ingestion
-hazardous in inhalation
-liquid spray and mist may produce tissue
damage, particular in eyes, mouth and
respiratory tract
-skin contact may produce burns
SAFETY MEASURES
-eye contact: flush for 15 min
-skin contact: flush for 15 min
-inhalation: get fresh air
*if further problems ensue seek medical
attention
Benedicts Reagent
Biuret Solution
Results
Part A: Testing Carbohydrates Stored as Starch
Test Tube
1
2
3
4
5
6
7
8
Unknown A
Unknown B
Substance
Distilled Water
Starch solution
Potato
Onion
Bread
Butter
Fruit juice
Milk
Observation
Yellow
Blue-black
Blue-black
Brown-yellow
Blue-black
Brown-yellow
Cloudy brown-yellow
White-yellow
Brown-yellow
Brown-olive
Conclusion
No starch
Starch present
Starch present
Little starch
Starch present
Little starch
Little starch
No starch
Little starch
Starch present
Unknown C
Brown yellow
Little starch
Part B: Test for Carbohydrates Stored as Glucose
Test Tube
1
2
3
4
5
6
7
8
Substance
Distilled Water
Glucose
Potato
Onion
Bread
Butter
Fruit Juice
Milk
Unknown A
Unknown B
Unknown C
Observations
Blue
Brown-red
Blue-green
Yellow
Green
Yellow-blue
Yellow-green
blue
yellow
Green
orange
Conclusion
No glucose
Very high
Very low
Moderate
Very low
Low
Low
No glucose
Low
Very low
High
Part C1: Testing for Solubility
Test for Lipids
Sample
Water Spot
Results
-stays in spot
-does not penetrate paper
-spreads quickly
-penetrates paper
Oil Spot
Part C2: Emulsification of Lipids
Tube 1
Tube 2
Unknown A
Unknown B
Unknown C
Not soluble
Not soluble
Soluble
Not soluble
Soluble
Part D: Testing for Proteins (Biuret Reagent)
Test Tube
1
2
3
4
Substance
D1 water
Protein source
Starch
Bread
Observation
Blue
Violet
Clear-cloudy
White-cloudy
Conclusion
No protein
High protein
Small protein
No protein
5
6
7
Butter
Fruit juice
Milk
Unknown A
Unknown B
Unknown C
Dark brown
Dark brown
Dark brown
Clear
Yellow
Light purple
Small protein
No protein
High protein
Small protein
Small protein
Small protein
Discussion
The lab showed that water tested does not contain starch, glucose or protein. The potato
contained starch and low glucose. The onion contained little amounts of starch and glucose. The bread
contained starch, low carbohydrates and no protein. The butter contained small amounts of starch,
glucose and protein. The fruit juice contained little starch and glucose however no amounts of protein
was found. The milk contained no starch, no glucose but high amounts of protein. An error may have
taken place when testing the milk and the bread. The bread absorbed the liquid so it was hard to tell
what the color of the solution was. The milk was difficult because of the white color it has makes it
difficult to see slight color changes.
Conclusion
The lab was able to show which substances contain amounts of starch, glucose and protein. The
unknown substances were also uncovered with what they may contain.