Name:
Laboratory Reflection: UV mutagenesis - Week 1
Instructions:
Make sure to scroll through the entire document to answer all questions. It would
also help with grading if you put your typed answers in a different (but readable)
color font
.
Save and upload your completed assignment to the associated assignment page on Canvas.
It is
the student’s responsibility to confirm that the correct file was submitted to Canvas by the due
date.
1.
In this week’s laboratory, you plated
trp1-289
yeast onto two different kinds of media (SD
trp- plates and SC plates).
a.
(1pt) What is the difference between
trp1-289
and wildtype yeast cells?
The trp1-289 cells will mutate but end up staying relatively close to their parent cells, but
wildtype yeast cells will mutate and change endlessly.
b.
(1pt) How can plating
trp1-289
yeast onto SD media allow you to test for a phenotypic
reversion? Be specific.
When growing on an SD media, we can see the reversion much more clearly.
2.
The original yeast culture you used to inoculate the SD-media plates should have quite a
high concentration of cells/ml. The solution you used to inoculate the SC medium plates is a
10
-4
dilution of the original.
a.
(1pt) What do you think would happen if you used a diluted yeast solution to
inoculate the SD (trp- medium) plates?
There wouldn’t be enough growth to determine a reversion.
b.
(1pt) What would happen if you used the concentrated original yeast culture to
inoculate the SC-media plates?
There would be too much growth, and we wouldn’t be able to get an accurate count like we can
with diluted amounts.
3.
(1pt) In the following picture, each row is a serial dilution of yeast plated on SC media.
One dilution was made from a culture that was mutagenized with UV light for an
extended period, one was mutagenized briefly, and one was a control (not mutagenized).
To the right of each Row (A, B and C) write the type of treatment (Extended UV, Brief UV,
or Control) that each dilution series received.
A
= Control
B= Extended UV
C= Brief UV
4.
Consider the relationship between UV exposure (e.g. UV exposure time) and cell death.
1
A
B
C
