Name Section: Question 3 In order to study genes involved in the progression of cancer you do gene expression analysis To do this you compare the mRNA levels of normal cells versus tumor cells. What you find from this experiment is that some genes are upregulated in the tumor cells i.e. they have an increase in the mRNA levels of a certain gene and that some genes are downregulated in the tumor cells meaning that they have a decrease in the mRNA levels of certain genes. You also have some genes whose mRNa levels stay the same a) What is the most likely function of the genes that are upregulated in the tumor cells? b)What is the most likely function of the genes that are downregulated in the tumor cells? c)What is the most likely function of the genes that are the same in tumor and normal cells? d) You find out later that one of the genes whose mRNA levels stayed the same actually plays a critical role in the progression of cancer. How can this be? e) You clone the gene from(d)and you discover that it is p21 as. You then take normal fibroblasts and overexpress this allele of the Ras gene in them. To your surprise the cell do not proliferate, but stop dividing. Give an explanation of for this outcome 7012fall2003Name:___________________________________ Section:_____ 7.012 fall 2003 4 Question 3 In order to study genes involved in the progression of cancer you do gene expression analysis. To do this you compare the mRNA levels of normal cells versus tumor cells. What you find from this experiment is that some genes are upregulated in the tumor cells i.e. they have an increase in the mRNA levels of a certain gene and that some genes are downregulated in the tumor cells meaning that they have a decrease in the mRNA levels of certain genes. You also have some genes whose mRNA levels stay the same. a) What is the most likely function of the genes that are upregulated in the tumor cells? b) What is the most likely function of the genes that are downregulated in the tumor cells? c) What is the most likely function of the genes that are the same in tumor and normal cells? d) You find out later that one of the genes whose mRNA levels stayed the same actually plays a critical role in the progression of cancer. How can this be? e) You clone the gene from (d) and you discover that it is p21Ras. You then take normal fibroblasts and overexpress this allele of the Ras gene in them. To your surprise the cell do not proliferate, but stop dividing. Give an explanation of for this outcome