Lab 2: Identifying Organic Macromolecules (30 points)

Due: Week of Septebmer 26, 2022 to Gradescope 

Name:_________John Gibson__________________________

1. (4 pts) What are the 4 organic macromolecules and their corresponding building block monomers (note: one of these does not have an actual monomeric unit)? 

Carbohydrate polysaccharides, their monomer is monosaccharides (glucose, fructose, etc)

Proteins, their monomer is an amino acid

Nucleic acids, their monomer is nucleotides

Lipid , monomer is either the lipid itself or a fatty acid subunit 

2. (4 pts) Match the following reagents/methods with the macromolecule they will identify in this week’s lab:

3. (3 pts) In your own words explain what a positive and negative control are and their respective purpose. 

The positive control experiment group includes the factor/attribute (chemical or physical) that will elicit a reaction. The purpose is to check that the experiment has a valid setup so that when a subject under testing contains the factor, it will elicit the same reaction and not fail to manifest the factor/attribute due to other experimental setup failures. This prevents a false negative when the subject contains the factor/attribute but fails to elicit a reaction due to a faulty setup.

The negative control experiment group excludes the factor/attribute that would elicit a reaction. The purpose is to check that the experiment has a valid setup so that when a subject under testing elicits a reaction, we can be sure that the reaction is not a false positive by the experiment setup (such as contamination).

4. (10 pts) Explain the results for each unknown (positive/negative for each test) and based on these what your best guess is for each unknown from the nutrition labels posted on Blackboard. 

Unknown (enter the unknown letter below)	Lipid	Protein	Simple Sugar	Starch	Identification based on Nutrition Labels?
B	wet	doesn’t mix	doesn’t mix	doesn’t mix	Yes, Mineral oil
F	dry	very purple	blue	yellow	Yes, muscle milk
H	dry	yellow	brown	yellow	Yes, either apple or lemonade juice
A	dry	blue	slight color change to brown	black	Yes, Meringue powder

Explain/Justify your Identification of each unknown below:

B is Mineral. Oil is just long chain hydrocarbon , similar to lipid, would not evaporate at room temp. It matches B

F is Muscle Milk, low in fat at 2g, high in protein at 40g, and almost no sugar.

H is Apple Juice, just sugar in the label. It matches H and is yellow golden in color

A is Meringue powder, which has a small amount of sugar.  It is not pasta or rice because it has no protein.

5. (2 pts) Would Biuret show a positive result in a test tube full of individual amino acids? Explain (think about what the test specifically detects). 

No. The Biuret reaction is a complexation of Cu+ ions with peptide bonds. Individual amino acids don’t have peptide bonds.

6. (1 pt) What is name of the macromolecule that Lugol’s Iodine detects? Which specific type of this macromolecule does Lugol’s Iodine detect (recall the molecular structure and how the detection works)? 

Starch. The amylose helix interacts with iodine triplets. 

7. (2 pts) Where and in what form to plants store excess glucose, how does this compare to humans?

It stores glucose in starch in the roots. This is compared to glycogen stored in the liver and muscles in humans.

8. (2 pts) What type of bond links two amino acids together?  What type of bond links two monosaccharides together?

The peptide amide bond links two amino acides.

A glycosidic ether bond links two monosaccharides.

9. (2 pts) What are the 4 common elements found regularly in organic molecules?

Hydrogen, Oxygen, Nitrogen, Carbon.