The AURKA gene encodes an enzyme that helps assemble the spindle fibers, which signals the cells to continue through mitosis. When researchers analyzed the levels of the AURKA protein in different types of cancer cells, they found that cancer cells expressing high levels of AURKA protein had more tripolar divisions when treated with paclitaxel, than did cancer cells expressing low levels of AURKA protein. Required:
a. Describe the situations in which a normal human cell would enter the cell cycle and undergo mitotic cell division. Explain how spindle fibers help ensure the products of mitosis are two identical cells with a full set of chromosomes.
b. Based on the data, identify the lowest level of paclitaxel that will allow for at least 50% of the cells to be tripolar. From the start codon through the stop codon, the length of the fully processed AURKA mRNA is 1,212 nucleotides. Calculate the number of amino acids in the polypeptide chain coded for by the mRNA.
c. Predict the effect of a mutation that prevents the expression of AURKA on a normal (noncancerous) cell.