Mutations and Survival Rate of Yeast exposed to Ultra Violet Radiation
Dennis Uzar, Nick Luz
L113, Monday, 5:45 PM Section 14987
February 27, 2012
AI: Karen Bohorquez
Using UV irradiation, the effects of UV light on
were studied and
related to all living cells and DNA.
Seven plates in a tryptophan deficient medium (SD)
were plated with an original undiluted haploid culture and seven plates containing
tryptophan (SC) were plated using a 10
diluted haploid culture.
These 14 agar plates
were tested in pairs under a certain allotment of UV exposure.
The results showed that
percent survival in the SC medium decreased as the time of UV exposure increased and
the percent mutations in the SD medium increased as the tome of UV exposure increased.
These results occurred because the UV light damaged the DNA of the yeast in the SC
medium thus being deadly, while the yeast in the SD medium were beneficially mutated
back into the wild type which allowed them to replicate.
This experiment supports the
hypothesis that UV light can damage and mutate DNA in living cells.
An Eppendorf tube containing an overnight culture of Saccharomyces cerevisiae
(yeast) that had the
allele was created by incubating the culture overnight at 30
°C and supplied for the experiment as the original haploid culture.
Four other Eppendorf
tubes were labeled 10
, and 10
and filled with 900 µl of H
O to prepare for the
For the tube labeled 10
, 100 µl of the original haploid culture was
pipetted and mixed thoroughly to create the first dilution.
For the proceeding dilutions,
pipet tips were changed each time and 100 µl from the 10
tube was pipetted into the 10
The suspension from the 10
tube was mixed and 100 µl was pipetted into the 10
tube and mixed again.
Lastly, 100 µl of solution from the 10
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