We hypothesized that the amount of UV radiation exposed has a negative correlation with yeast genetic stability, which ultimately determines the number of yeast colonies. In this experiment, yeast cells were treated with UV radiation, protected by photoprotective agents with different strength (in ascending order: Sunscreen #2, #1, aluminium foil). After letting it grow for seven days at 37 degrees, some grown colonies were counted to determine the effectiveness of photoprotective agents. After comparing collected results with the controlled group, we conclude that sunscreen #2 absorbs nearly zero UV radiation (0 yeast growth). Sunscreen #1 has some photoprotective effect (observed yeast growth). Theoretically, aluminium foil should be the most effective photoprotective measure as it reflects the most EMR radiation; however, results are not consistent with the hypothesis as some experiment groups obtained more yeast growth compared to that of sunscreen #1. This may be caused by several factors: 1) not all yeast cells are at the same physical shape (age, damage etc.). 2) Not all Petri dishes had the same amount of yeast cells cultured in them. 3) Different degrees of other contamination may also influence the outcome. Results partially agree with our hypothesis. UV radiation directly causes damage at a cellular level by inducing DNA mutations, and supresses the immune response of eukaryotic multicellular organisms by supressing T-cells (Green et al. 2011). In this experiment, yeast (unicellular eukaryote) was exposed to UV radiation which would increase the likelihood of mutating its DNA. Thus, the regular cellular activities and functionality were affected and would result in cell death. Sunscreens contain active ingredients that absorb electromagnetic radiation emitted between 290-400 nm. Photoprotective agents can reduce or prevent damage that caused by UV radiation. SPF is an indication of the product’s ability to block/absorb UVB radiation (280–315nm)...
Cited: Ade`le C. Green, Gail M. Williams, Valerie Logan, and Geoffrey M. Strutton. 2011. Reduced Melanoma After Regular Sunscreen Use: Randomized Trial Follow-Up. JOURNAL OF CLINICAL ONCOLOGY. 29: 257-263
Nicola A. Quatrano and James G. Dinulos. 2013. Current principles of sunscreen use in children. CURRENT OPINION. 25: 1.
T.L. Diepgen, M. Fartasch, H. Drexler, J. Schmitt. 2012. Occupational skin cancer induced by ultraviolet radiation and its prevention. British Journal of Dermatology. 167(2):76-84.
Please join StudyMode to read the full document