Introduction or purpose
There are four macromolecules in living organisms which are proteins, carbohydrates, lipids,
and nucleic acids. These are used by our cells and often obtained through foods we eat. The
purpose of this laboratory is to determine the presence of key macromolecules in food and to
relate these organic compounds to life processes. It is very important to realize because all of
the organisms on earth use all of the biomolecules in our cell.
In this lab, the hypothesis is if carbohydrates, protein, and lipids are present in the food
slurry, then each will test positive in the presence of their respective reagents. Since McMush
laboratory activity examines chemical tests for the presence of carbohydrates, lipids, and
proteins found in food samples, we learn more about the existence of macromolecules in
living organisms. So we can understand what macromolecules are and what macromolecules
are in each organism. I would like to know why each solution is positive or negative. Seeing
positive and negative responses to where the macromolecules exist can further enhance my
understanding about macromolecules.
Materials
beaker, hot plate, well plate, tongs, test tubes, test tube rack, McMush food slurry, glucose
control, starch control, protein control (egg solution), lipid control (oil), distilled water,
Benedict’s Solution, Lugol’s Solution, Biuret’s Solution, Sudan Solution
Methods or Procedure
Monosaccharide test:
1.Place 3 ml each of glucose solution, distilled water, and the food slurry in seperate test
tubes.
2.Add 5 drops of Benedict’s solution to each test tube and gently mix.
3.Leave the test tubes in the water bath for 5 minutes or until you start to see a color change.
4.Record color on the data table.
Polysaccharide test:
1.Place 3 ml each of starch solution, distilled water, and the food slurry in seperate wells on
the well plate.
2.Add 3 drops of Lugol’s Iodine Solution to each well.
3.Observe any color change and record the results in the data table.
Protein test:
1.Place 3 ml each of egg solution, distilled water, and the food slurry in seperate wells on the
well plate.
2.Add 10 drops of Biuret’s solution to each well and mix carefully.
3.Observe any color change and record the results in the data table.
Lipid test:
1.Place 3 ml each of vegetable oil, distilled water, and the food slurry in seperate wells on the
well plate.
2.Add 5 drops of Sudan III Solution to each well
3.Observe any color change and record the results in the data table.
Data and Results
Result of Test Performed on Known Substances
Test Performed
Substance Tested
Positive Test Color
Negative Test Color
Monosaccharide
Carbohydrates
Benedict's solution
Orange to brick-red
color
Blue
Polysaccharide
Carbohydrates
Lygol’s solution
Dark Blue
Amber
Proteins
Biuret’s solution
Violet
Blue
Lipids
Sudan III solution
Layers or Clumps
No layers or no
clumps
Result of McMush Test
Macromolecule
Food Substance
Result
Water Result
Food Slurry Result
Monosaccharide
Glucose solution:
Negative
No change
Negative
No change
Negative
No change
Polysaccharide
Starch solution:
Positive
Dark blue
Negative
Amber
Negative
Dark Amber
Protein
Egg solution:
Positive
Violet
Negative
Blue
Negative
No change
Lipid
Vegetable Oil:
Positive
Layer
Negative
Fat
Positive
Chunky layer
The results of monosaccharide on Benedict’s solutions are negative of glucose, negative of
water, and negative of food slurry. Because glucose, water, and food slurry has no change.
The results of polysaccharide on Lygol’s solutions are positive of starch solution, negative of
water, and negative of food slurry. Since Lygol’s positive color is dark blue and negative color
is amber, the starch solution is positive because it changed to dark blue. And water and food
slurry are changed to amber so both are negative. The results of protein on Biuret’s solutions
are positive of egg solution, negative of water solution, and negative of food slurry. Since
Biuret’s solution’s positive color is violet and the negative color is blue, the egg solution is
positive because it changed to violet. Water changed to blue which is negative, and food
slurry has no change which is also negative. The results of Lipid on Sudan’s solutions are
positive of vegetable oil, negative of water, and positive of food slurry. Since Sudan’s positive
result is layers or clumps and negative result is no layers or clumps, vegetable oil is positive
because it is with layers. Water is negative because there is no layer. Food slurry has a chunky
layer, so it is positive.
Discussion or Analysis
The hypothesis was if carbohydrates, protein, and lipids are present in the food slurry, then
each will test positive in the presence of their respective reagents. Monosaccahride’s glucose
solution and food slurry were both negative so it is accepted by the hypothesis. Lipid’s
vegetable oil and food slurry were both positive so it is accepted by the hypothesis. However,
when starch solution and egg solution were positive, their food slurries were present
negative. It means that a happy meal has no protein and polysaccharide. But if I made a
mistake, looking back on what I did, I am not sure that I put the right amount of solutions.
Probably this is the reason for the wrong result if I made a mistake.
Conclusion
A happy meal at McDonald's does not have nutritional value because three biomolecules are
not present in the meal. In the data, when the sudan’s solution was added into the McMush,
it got a chunky layer. When other macromolecules were present negative in McMush, only
lipids were present positive. It means only lipids are in a happy meal and it can not afford
enough nutrients to people. Starch, protein, and lipids are three biomolecules essential for
our nutrition. Therefore a happy meal does not have enough nutrition, so we should eat
other food that has three biomolecules.
Reference
https://www.markedbyteachers.com/international-baccalaureate/biology/the-effect-of-indicat
ors-on-the-presence-of-macromolecules-in-a-mcmush-slurry.html