Question 1 continued a) How do you explain the presence of sequences complementary to the oncogene in the DNA from healthy human and mouse samples? Why don' t they have cancer? b)Why is the hybridizing band from sample l a different size than that from sample 5? c)For each cancer examined above, based on the autoradiogram, choose the most likely mechanism of transformation and explain your choice 1)point mutation within the gene 2 )chromosomal rearrangement involving the gene 3)gene amplification 4)oncogenic retroviral insertion. Question 2 You are studying the cell cycle in haploid yeast cells. You isolate a cell that is a 25 C, but arrests at 36C at the point in the cell cycle where the expression of the at temperature-sensitive cell division cycle(cdc)mutant, cdcX-. cdcX-grows normal normal cdc gene is required To determine where in the cell cycle expression of cdkX is required, you design experiments based on the following facts 1)The drug nocodazole arrests, but does not kill yeast in mitosis(M phase) 2)Cell density can be measured to determine if the yeast cells have completed a cell division. For your experiments You incubate cdkX- cells at 25 C with nocodazole until all the cells are synchronized. You then shift the cells to 36C and remove the nocodazole The cells divide once and then arrest You incubate cdkX-cells at 36 C until all arrest. You then add nocodazole and shift the cells to 25 The cells arrest without dividing. a)Given these experiments you can assume that the protein encoded by the cdkX gene is not required at what phase(s)of the cell?3 Question 1 continued a) How do you explain the presence of sequences complementary to the oncogene in the DNA from healthy human and mouse samples? Why don't they have cancer? b) Why is the hybridizing band from sample 1 a different size than that from sample 5? c) For each cancer examined above, based on the autoradiogram, choose the most likely mechanism of transformation and explain your choice: 1) point mutation within the gene 2) chromosomal rearrangement involving the gene 3) gene amplification 4) oncogenic retroviral insertion. Question 2 You are studying the cell cycle in haploid yeast cells. You isolate a cell that is a temperature-sensitive cell division cycle (cdc) mutant, cdcX-. cdcX- grows normally at 25 °C, but arrests at 36 °C at the point in the cell cycle where the expression of the normal cdcX gene is required. To determine where in the cell cycle expression of cdkX is required, you design experiments based on the following facts: 1) The drug nocodazole arrests, but does not kill yeast in mitosis (M phase). 2) Cell density can be measured to determine if the yeast cells have completed a cell division. For your experiments: • You incubate cdkX- cells at 25 °C with nocodazole until all the cells are synchronized. You then shift the cells to 36 °C and remove the nocodazole. The cells divide once and then arrest. • You incubate cdkX- cells at 36 °C until all arrest. You then add nocodazole and shift the cells to 25 °. The cells arrest without dividing. a) Given these experiments you can assume that the protein encoded by the cdkX gene is not required at what phase(s) of the cell?