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Collin College BIOL 1408 Unit 4 Macromolecules Packet
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- BIOL 1408
- Institution
- Collin College
Collin College BIOL 1408 Unit 4 Macromolecules Packet
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Unit 4Macromolecules
This lab uses the following hazardous chemicals:
I. Benedict’s Indicator Reagent
II. Biuret Indicator Reagent
III. Iodine Solution
IV. Sudan IV Solution
As a result students are required to wear, at minimum, Goggles & Gloves.
Abstract
There are four broad classes of macromolecules that can be found in living systems.
Each type of macromolecule has a characteristic structure and function in living
organisms. You can use your knowledge of the basic structure of each macromolecule
to perform tests in the lab that detect the presence or absence of key functional groups
or overall characteristics in various substances. In this lab, you will utilize the
following procedures to detect three of these macromolecules in everyday household
items- note what each procedure will detect in which macromolecules.
Structure/ Molecule Structure/Molecule Found
Test (Reagent)
Detected: in:
Reducing sugars (sugars
with a free aldehyde or
Benedict’s Carbohydrates
ketone group; typically
mono or disaccharides)
Iodine Starch Carbohydrates
Sudan IV Water insoluble substances Lipids
Biuret’s Peptide Bonds Protein
Figure
1.
A
list
of
the
detection
reagents
used
to
reveal
the
presence
of
specific
macromolecules.
Use the Internet or a library as a source and list three examples of reducing sugars:
a. Reducing Sugar: __________________________
Found in: ___________________________________
b. Reducing Sugar: __________________________
45
, Found in: ___________________________________
c. Reducing Sugar: __________________________
Found in: ___________________________________
Detection Reagent Explanation of Detection
Contains Copper Sulfate. Copper binds to
oxygen in the free aldehyde or ketone
Benedict’s group and the Copper Oxide that is formed
results in a brown color.
Iodine interacts with and binds to a
structure in the starch molecule, the new
Iodine structure transmits a dark bluish black
color
Water insoluble substances interact with
Sudan IV other water insoluble substances
Contains Copper Sulfate and Sodium
Hydroxide. Copper Sulfate actively binds
to the peptide bonds found in proteins, and
Biuret’s the structure formed transmits a violet
color in an alkaline (basic) environment,
which is provided by the presence of the
NaOH.
Figure
2.
Chemical
explanations
for
the
colorimetric
changes
observed
in
macromolecule
detection
tests.
4.1 Designing Experimental Controls
Introduction
Because you are going to be testing for the presence of different macromolecules in this
lab, there are several important steps that you must first take to ensure that you properly
interpret your results. In order for you to know which of the macromolecules are present
in your samples, you must initially set up controls. Controls are samples or trials with an
outcome that is already known. There are positive controls, which give positive results
(Example: In the case of the reducing sugars test, a sample containing a known reducing
sugar). There are also negative controls, which give negative results (Example: In the
case of the reducing sugars test, a sample that contains no reducing sugars).
For the purpose of this experiment, we have provided you with the following:
1% Glucose Solution
Egg Albumin (used previously in the Spectrophotometry Unit)
Vegetable Oil
1% Starch Solution
46
, Each of the above mentioned solutions will be used as a positive control for one of
the macromolecule tests. Using the information from lecture and your lab manual,
please state the macromolecule that these controls will help you identify.
Results
Solution Positive Control For
1% Glucose Solution
Egg Albumin Solution
Vegetable Oil
1% Starch Solution
Figure
3.
Determination
of
solutions
used
for
positive
controls
for
each
type
of
macromolecule.
Additionally, you will want a negative control for each test. Can you think of a solution
that would produce a negative result for each and every one of the tests listed above?
4.2 Lipids and Their Chemical Properties
Introduction
Unfortunately, the relative concentrations of lipids in each of the household substances
are too low to detect using any kind of test available in this laboratory setting. Instead, the
following experiments are intended to further your understanding about the chemical
properties of lipids. Here you will observe the interaction between lipids and water, as
well as the detection reagent that is used to indicate the lipid component of your solution.
Finally, you will look at the effect that an emulsifier has on lipids. An emulsifier is a
substance that has both hydrophobic and hydrophilic properties on different portions of
the molecule.
Answer the following questions in preparation for this experiment:
Observe the lipid solution provided as your standard. Is it a saturated or unsaturated fat?
How do you know?
During the remainder of the lab, you will be working with hazardous substances. Goggles
and Gloves must be worn from this point on!
47
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