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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 Summary: Using UV irradiation, the effects of UV light on S. cerevisiae 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 10-4 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. Methods: An Eppendorf tube containing an overnight culture of Saccharomyces cerevisiae (yeast) that had the trp1-289 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 10-1 , 10-2 , 10-3 , and 10-4 and filled with 900 l of H 2 O to prepare for the serial dilutions. For the tube labeled 10-1 , 100 l 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 l from the 10-1 tube was pipetted into the 10-2 tube. The suspension from the 10-2 tube was mixed and 100 l was pipetted into the 10-3 tube and mixed again. Lastly, 100 l of solution from the 10... View Full Document

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