Worksheet 7
Fractionation and Chromatography
20 points
Name:
Section:
Date Turned in:
Introduction:
1. (2 pts) Go to the website (faculty.ycp.edu/~abotyriu) and find the fractionation
lab under Molecules, Genes, Cells Lab Resources.
Click on “Pigment Structures”.
This page shows you chlorophyll a and b, beta carotene (a carotenoid) and two
types of xanthophylls.
Which one of the following best describes all of the pigments? Circle ONE.
a. they are all nonpolar amino acids
b. they are all polar lipids
c. they are all amphipathic phospholipids
d. they are all polar carbohydrates
e. they are all short polypeptides made up of polar and nonpolar amino acids
f. they are all hydrophobic lipids
g. they are all types of nucleic acids
2. (3 pts) Do you thing you could fractionate proteins using a centrifuge? Explain
why or why not. Include any assumptions you are making in your answer.
Materials and Methods:
2. (3 pts) Why did we mix chloroplasts with acetone?
3. (2 pts) If we used the ST-MICRO rotor for the separation of chloroplasts from
the supernatant, at what RPM would you need to set the centrifuge?
Results:
4. (2.5 pts) What was the most non-polar pigment in the plant extract? Give
quantitative or semi-quantitative evidence for your answer.
5. (2.5 pts) How did you know that the first structures to form a pellet were starch
grains?
Discussion:
6. Chromatograms from different species can be used to infer evolutionary
relationships. The assumption is that species that are closely related to each other
will share similar photosynthetic pigments. Thus, the common ancestor would have
pigments shared by all descendant species. It is rare for a species to evolve a
pigment, only to have it go away and a new pigment take its place.
Go to the website (faculty.ycp.edu/~abotyriu) and find the fractionation lab under
Molecules, Genes, Cells Lab Resources.
Click on the “chromatograms” link.
You will see chromatograms prepared in the same way they were in our lab. Each
was prepared using a different species, which is listed below the image. Some
species are closely related and some are very distantly related to green plants.
(2.5pts) Which species do you think appeared on the planet first and gave rise to all
of the others? Explain your answer.
7. (2.5 pts) Critical analysis! The following diagram was taken from a lab manual
that was describing how to perform plant fractionation on peas (just like we did).
However, there are some major flaws in this diagram. Describe one. Hint: they
are isolating different organelles than we did, this isn’t a flaw.
5000g x 20 min