3.
(from an old exam) You are studying a gene in yeast that codes for glucose kinase. Thus, you
decide to investigate the use of RNA interference to reduce expression of the enzyme. Much to
your dismay, you realize that yeast do not contain the genes for Dicer and Slicer, and thus does
not have an active RNA interference pathway. Therefore, you decide to create yeast with
human RNA interference enzymes to bypass this problem. Analyze the experiments below and
answer the following questions, Assume that human RNA interference enzymes are
synthesized properly and are functional in the yeast.
A. You add the Dicer gene (but not the Slicer gene) to the yeast, and Dicer protein is
synthesized. Then, you add a 500 basepair double-stranded RNA corresponding to the glucose
kinase mRNA to the yeast. Do you expect to observe silencing (degradation) of the glucose
kinase mRNA? Briefly explain. [2-4 sentences]
B. You add the Slicer gene (but not the Dicer gene) to the yeast, and Slicer protein is
synthesized (and generates a functional RISC). Then, you add a 22 basepair small interfering
(siRNA) corresponding to the glucose kinase mRNA to the yeast. Do you expect to observe
silencing (degradation) of the glucose kinase mRNA? Briefly explain. [2-4 sentences]
