Caffeine Inhibited Saccharomyces Cerevisiae s Dna Repair...

Caffeine inhibited Saccharomyces cerevisiae’s DNA repair system by disrupting its recombinational process post UV-irradiation Alexa Alana, Annie Cribb, Tommy Paranzino Biology 131- L8 ABSTRACT Saccharomyces cerevisiae was tested for the effects of ultraviolet (UV) irradiation in the presence of caffeine to observe whether the drug would enhance or inhibit the DNA’s recombinational repair process after the yeast has experienced UV damage. We hypothesized that caffeine would obstruct the yeast’s DNA repair process by interrupting its recombinational process post UV-irradiation, and we predicted that increasing caffeine levels would decrease percent survival. By exposing the yeast to three different caffeine concentrations (0, 5, and 10 mM) at 1x104 microjoules/cm2 of UV irradiation, we measured the effects of caffeine dosage on DNA repair. We reported that an increase in the caffeine concentration level causes a decrease in the percent survival, supporting our hypothesis. Caffeine, therefore, can be perceived as a model compound in the nullification of DNA-damage checkpoints. Moreover, the inhibition of the recombinational repair process provides a molecular e xplanation for the reduction of DNA-damage checkpoint responses and for the increased UV-sensitivity of caffeine-treated yeast cells. INTRODUCTION Ultraviolet (UV) light is an intermediate source of energy that can damage cells. The DNA in cells is especially sensitive to UV irradiation. The rings of the