K101 LAB EXERCISE 3
MACROMOLECULES IN THE DIET:
CARBOHYDRATES, LIPIDS, AND PROTEINS
Please bring in a small amount (1 tsp. or less) of a solid food from home!
All life is largely composed of compounds made from carbon, hydrogen, oxygen and
These atoms can be arranged by cells to make sugars, fatty acids, amino acids and
nucleotides - building blocks that form more complicated macromolecule like carbohydrates,
lipids, proteins, and nucleic acids.
Of these 4 major groups of macromolecules, the first three not
only provide that basic ‘building materials’ from which our cells and tissues are constructed, but
also provide us with cellular energy (measured in kilocalories) via the covalent bonds between
(The last group, nucleic acids, make up DNA and RNA.
Although we typically
consume the DNA and RNA of other organisms, we do not derive a significant nutritive value
from these macromolecules, but these polymers can be broken down to their constituent parts
and re-used by our cells).
During today’s lab, you will learn to do simple
, or tests, for common
macromolecules like sugars, lipids, and proteins, and then use your knowledge of these assays to
determine the types of macromolecules commonly found in the foods we eat.
During the last
two parts of the lab, you will do an unknown determination of a common food substance, and
you will also devise a way to test a solid food (from the lab or from a sample you bring in) for
the presence of common macromolecules.
Please read through this handout carefully before lab
There are many things to do,
and it is to your benefit to be as organized as possible so that your time in the lab is spent doing
the work to be done rather that trying to figure out what needs to be done by reading through the
lab in class!
Good organizational skills and teamwork
between you and your lab partner (and
between the other groups at your bench) will make the procedures go smoothly.
You will also
see the importance of labeling tubes clearly and making accurate measurements.
(These are also
important skills for your future as a scientist or medical professional).
If you have any questions
before proceeding, just ask your TA.
Most of the substances we will use today pose no danger in
the lab, but continue to follow lab procedures for safety and disposal of waste.
After completing all your experiments, please make sure to clean up your
Place tubes for each test BACK IN ORDER in the correct test tube rack.
used tips and microfuge tubes.
Place pipettemen back in their stands.
Wash out your spot
plate and dry it upside down on the tray on your bench.
Do not throw away any screw-capped
tubes – let your TA know if solutions need to be replaced.
THANKS for your cooperation