9. (2 pts.) A student performs a Southern blot and immediately probes the blot with a P 32 radioisotope labelled DNA probe. She then washed with high stringency washes. After putting the membrane on an imaging plate for the correct amount of time she scans the imaging plate in a digital imager. The image on the screen is completely black, what would most likely cause of that and what would you do to correct the problem? 10. (3 pts.) What is metal affinity chromatography AND what would you use to elute a His-tag protein from a nickel affinity column? 11. (4 pts.) What components should be in SDS-PAGE sample buffer and why? 12. (3 pts.) Why would the components you listed in the previous question not be appropriate for Isoelectric Focusing (IEF) sample buffer? What should you use in an IEF sample buffer and why? 13. (4 pts.) Determine if the following conditions would cause a particle in a centrifuge tube to increase (), decrease (), or have no effect (NE) on its velocity away from the center of rotation during centrifugation. The angular momentum (rpm) increases The particle enters a region of increased media density The media frictional coefficient goes up The particle forms a dimer during centrifugation and its mass doubles. 14. (3 pts.) In two-dimensional gel electrophoresis, does it matter which dimension is done first? Explain