You are studying the MBOC gene, which is thought to underlie the interesting observation that cell biologists have thick skin. A map of this gene with the transcription unit (= place that is copied into RNA) indicated by the large black arrow and surrounding DNA is shown below. Several of your brave classmates have donated several small fragments of their skin for the following experiment: On the day of the cell biology midterm you isolate nuclei from skin cells of a student taking both Eukaryotic Molecular Biology (EMB) and Cell Biology as well as from control skin cells of a student taking only EMB, a student taking only Cell Biology, and also from poor unsuspecting student in the History department. You lightly treat these nuclei with DNAse I (i.e. a low concentration for a short period of time), and then extract the genomic DNA and digest it completely with Eco RI. You separate these digested DNAs on a gel, transfer them to a membrane and probe them with the probe shown below. You also extract RNA from these cells, perform a northern blot and probe it with the same probe. A restriction map of MBOC and the results of the Southern and northern blots are shown below. a. What can you conclude from the Northern blot? b. In the Southern blot, what does the 13 kb band represent? c. What do you think the ~4kb band represents? d. What do you think the ~8kb band represents? Mark it on the map above. e. The 8 kb band is observed in lanes 1 -3 but not in lane 4. What is a possible explanation of this? f. Propose a hypothesis about MBOC gene regulation that relates the results from the Southern and northern blots.