Research the Literature on your Own

1. What experimental techniques are used to measure forces in the picoNewton to nanoNewton range? Describe the theory behind the technique and list at least two biological applications for each technique.
2. Describe in detail the events of actin-based motility in a eukaryotic cell or bacterium of your choosing. Next, use metaphors to describe each event in the process.
3. Actin polymerization drives the motility of Listeria and the protrusion of the leading edge of many motile cells.  The speed of cell movement can vary over a wide range, from about 1 micron per second (for chemotaxing neutrophils) to about one micron per hour (for some fibroblasts).  Listeria moves at a speed of about 0.2 microns per second in epithelial cells but up to five times faster in macrophages.  What might cause the speed of actin-based motility to vary so much?  How could you test your ideas?