You have two beakers as depicted below.  Both are split in the middle and contain a semipermeable membrane. Both also contain a solute which cannot cross the semipermeable membrane by itself; the amount of solute is different on both sides of the beaker. Beaker #2 contains transporters embedded in the semi-permeable membrane that will allow the solute to pass.    You leave the beakers this way for a few hours and then come back to observe the results. What is most likely to happen?  

Methods in Cell Biology Short Answer Section (10 pts)

SA2c. (5 pts) Describe how CHIP28 (aquaporin) was shown experimentally to be a water channel.  Include a description of both the procedure and the result. (Your answer should include 5 steps).  1. 2. 3. 4. 5.

Membranes Short Answer Section (10 pts)

Which type of protein sorting involves SRP?

Researchers interested in studying possible interactions between lamellipodin (Lpd) and Mena performed the experiment below.  Lpd-FP4-2Mito is a fusino protein consisting of Lpd, the FP4 domain which has been shown to bind to Mena, and the 2Mito domain which has been shown to bind to the mitochondria.  The Lpd-Pro-Mito fusion protein is similar except that the FP4 domain has been replaced with a bunch of prolines that don’t really do anything other than act as a spacer.    Look at the immunofluorescence images and indicate which of the following was the most important result of this experiment.

Part II: Short Answer (6 questions, 5-10 points each) 40 points

You discover two new proteins named nooblin1 and nooblin2 that are present in cow taste buds. Under normal conditions both nooblin1 and nooblin2 are resting on the inner leaflet of the plasma membrane next to an ion channel involved in detecting sour taste.  You form a hypothesis that nooblin1 helps bring nooblin2 to the plasma membrane.  Which of the following statements is the best rationale that supports this hypothesis?

During endocytosis, substances are transported into the cell by which of the following events?

What would be a good positive control for a typical immunofluorescence experiment?