Molecules

3.1 Proteins
Table 3.2 Biuret Test
Tube
Contents
Final Color
Conclusions
1
Distilled water
Transparent, light blue, navy
Possibly little protein with clear peptide or no protein at all
2
Albumin
Dark Purple
Proteins are present with purple peptides
3
Pepsin
Purplish blue, darkish blue
Proteins are present with purple or black colored peptides
4
Starch
Light blue, really clear
Possible little protein with clear peptide or no protein at all
Our results are correct because water and starch should not contain protein (starch is a polysaccharide but not of an amino acid) and therefore remained blue unlike Albumin and Pepsin which do contain proteins causing them to turn into a different color.
Test tube # 1 is the controlled sample; a controlled sample is an experiment under regular conditions. Experiment Procedure include controlled sample in order to indentify the difference between the regular conditions and the experimented conditions.

3.2 Carbohydrates
Table 3.3 Iodine (IKI) Tests for Starch
Tube
Contents
Color
Conclusions
1
Water
Dark amber, maple syrup
Does not contain starch
2
Starch Suspension
Dark amber red, almost black
Contains starch
3
Onion Juice
Ketchup red, gold tint
Contains a slight amount of starch
4
Potato Juice
Black brownish
Contains starch
5
Glucose solution
Amber red
Does not contain starch
Our results were accurate and did not contain any unexpected results. Since water and Glucose shouldn’t contain starch they appeared to be yellowish-brown. But starch suspension, onion juice, and potato juice should contain starch and therefore changed color.
Potato:
.
.
Onion:
Under the microscope onion did not contain starch, but after some research, I have discovered that onions actually contain glucose, a component of starch, but when tested with iodine for starch (as we did in class) it will result negative because glucose is a simple sugar.

Table 3.5 Benedict’s Reagent Test
Tube
Contents
Color (After Heating)
Conclusions
1
Water
Dark blue
Contains no sugars
2
Glucose solution
Forest green
Contained very low amount of sugar
3
Onion Juice
Bright orange
Contained High amount of sugar
4
Potato Juice
Turquoise
Contained very low amount of sugar
5
Starch Suspension
Electric blue
Contained no sugars
In table 3.5, test tube 1 served as the controlled sample
When table 3.3 and 3.5 are compared these are the ending results:
Water is the controlled sample and does not contain sugars
Onion Juice contains sugars as well as potato juice
Glucose is stored as starch in potatoes but not so much in onions. This helps explain the results in table 3.5 because since potato juice stores glucose as starch (proven in table 3.3) it showed that it contained less sugar not in the form of starch, but when onion juice was tested, it resulted in containing small amounts of starch (proven in table 3.3) but high amounts of sugar not in the form of starch.

Starch Composition
Table 3.6 Starch Composition
Tube
Contents
Color Change
Conclusions
1
Water & Spit
Clear blue, floating particles (bubbles)
No sugar or maltose
2
Starch & Spit
Blue at bottom and gradually become white as you go up (Spectrum goes from blue to white) and substance is very thick
Some maltose because it became clear and thick
Starch is composed of sugars (preferably glucose monomers)

Test for Lipids
Table 3.7 Test for Lipids
Sample
Observations
Conclusions
Water Spot
Water Spread out instantly consuming almost 3 times the original radius of the droplet out of the square paper. After 5 min it had almost spread out across 90% of the paper and had successfully penetrated the paper but also evaporated a little.
Water is not a fat because it started evaporating a little and didn’t leave an oily spot
Oil Spot
Started to spread out at a very slow and gradual rate, and left a shine. After 5 min it still remained on top.
Oil is a fat because it didn’t evaporate and left an oily spot

Emulsification of lipids
Test tube 1: Vegetable oil is not soluble in water
Test tube 2: The oil seems to have been distributed in the water, though it has not been dissolved.
Table 3.8 Emulsification
Tube
Contents
Observations
Conclusions
1
Oil Water
Large bubbles of oil in the water
Oil is non-polar and therefore did not dissolve in the water
2
Oil Water Emulsifier
Seems to be like a huge cell. Small particles enclosed in a large circle
The emulsifier helped distribute the oil among the water
Test tube 1 looked like 2 different layers to the unaided eye. But when it was closely examined under a microscope, it showed a few bubble in the water. Similarly to the unaided eye view, the oil is still separated from the water.
Test tube 2 looked as if the oil had dissolved in the water when viewed without the microscope. But when it was magnified, it showed that the oil had not dissolved, instead it had only been dispersed into the water.

3.4 Testing the Chemical Composition of Everyday Materials and an Unkown
Table 3.9 Everyday Materials and Unknowns
Tube
Sugar
Starch
Protein
Lipid
1
Baby/Solid Blue
Black
Light Blue Clouds
Expanded fast
2
Cloudy Turquoise
Mud/dark green
Golden dirt rain
Yellow in Center
3
Forest Green
Dark amber
Foggy Purple
Expanded slowly
4
Crystal dark/sky blue
Muggy orange
Foggy Purple
White Substance in middle
5
Clear blue
Cloudy amber
Clear Purple
Expanded very fast then slowed down
Yes, there are many materials that resulted positive in multiple organic compounds. Such as Test tube number 3, which contains sugars and expanded slowly meaning it’s a lipid.
One type of food would be a potato (containing starch and sugars) or milk (containing sugars and proteins)

Laboratory Review 3

1. Peptide Bond
2. Enzymes and/or Catalysts
3. Amino Group and Carbonyl Group
4. Starch
5. Glucose or Maltose
6. Starch is stored as granules within cellular structures called plastids, including chloroplasts. By synthesizing starch, the plant can stock pile surplus sugar.
7. Starch is composed entirely of glucose monomers
8. Major function of fat is energy Storage
9. When fat is hydrolyzed, the fatty acid molecules are released
10. An emulsifier can help disperse a fat in water
11. Fats are non-polar
12. Proteins
13. A very long time because eggs do not contain much starch
14. Benedict’s Reagent

Thought Questions

15.) It is necessary to shake a bottle of salad dressing before adding it to the salad because most of the fats are on top and the other substances are on the bottom, and in order to get a good ration of fats to the other substances, a good shake is required.
16.) These results are considered negative because Blue is the original color of both of those reagents, which means that neither of them reacted meaning that the substance has neither starch or sugar. Since they were not present the result is negative. If they had been present the result would have been positive.