From the table, we can see there were no colonies growing on the tryptophan dropout and the isoleucine drop out, on all the medium plates except for the 1X dilution Tobacco medium plate. For the positive control, increasing concentrations of ethyl methane sulfonate (EMS) resulted in a decreasing number of colonies growing on the medium plates. This means that EMS is mutating the yeast in such a way that they would not be able to grow on the YPD. For each concentrations of the positive control, there are 3 different colours of the colonies with white being the most common. White means that there were no mutations to the yeast, which could explain why there are so many colonies as they are able to grow on the YPD plate. The red, red-pink and
…show more content…
There were one or two colonies found on the 10X dilution on YPD plates and 1X dilution on the tryptophan dropout plate. It is not surprising to see a colony on the 10X dilution on YPD plate but it is for the tryptophan dropout plate as there were no colonies on the rest of tryptophan dropout plates, including the positive and negative controls. This is the trp5 locus is heteroallelic, which would cause tryptophan auxotrophy, so D7 cells are not able to grow on tryptophan absent plates. But because there was a single colony found, it could be possible that there was mitotic gene conversion at the gene due to a mutagen, in this case tobacco, allowed the D7 yeast cell to grow. (Marshall, 2007) However, overall the result contradicts our hypothesis that tobacco can mutate D7 yeast cells as it commonly mutates the p53 gene, leading to cancer. This is because the mutation of this gene would result in a loss of its tumour suppressor function, leading to accumulation of cancer cells (Pfeifer, 2002). In our medium plates, there were hardly any colonies growing but unexpectedly, there were other organisms growing on the plate containing the YPD medium. This could be due to contamination in our experiment. There are a few possibilities for such results. Firstly, while trying to filter the mutagen, it was difficult as there were solid tobacco stuck and it took a long time to
There were one or two colonies found on the 10X dilution on YPD plates and 1X dilution on the tryptophan dropout plate. It is not surprising to see a colony on the 10X dilution on YPD plate but it is for the tryptophan dropout plate as there were no colonies on the rest of tryptophan dropout plates, including the positive and negative controls. This is the trp5 locus is heteroallelic, which would cause tryptophan auxotrophy, so D7 cells are not able to grow on tryptophan absent plates. But because there was a single colony found, it could be possible that there was mitotic gene conversion at the gene due to a mutagen, in this case tobacco, allowed the D7 yeast cell to grow. (Marshall, 2007) However, overall the result contradicts our hypothesis that tobacco can mutate D7 yeast cells as it commonly mutates the p53 gene, leading to cancer. This is because the mutation of this gene would result in a loss of its tumour suppressor function, leading to accumulation of cancer cells (Pfeifer, 2002). In our medium plates, there were hardly any colonies growing but unexpectedly, there were other organisms growing on the plate containing the YPD medium. This could be due to contamination in our experiment. There are a few possibilities for such results. Firstly, while trying to filter the mutagen, it was difficult as there were solid tobacco stuck and it took a long time to