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Review Questions
Why was a bundle of filaments, and not a single filament, used to measure the force generated by actin polymerization? In the optical trap experiment, how do individual filaments contribute to the total force generated by an actin bundle? For example, at a given time, is the measured force the sum of all the individual filaments within the bundle, a subset of the filaments, or a single filament? What conclusions can be drawn about force generation of branched networks? Why can’t optical tweezers be used to measure the force generated by the comet tail of Listeria? Name three mechanisms used by biological systems to generate force. Explain the microscopic and mesoscopic physical models of actin-based motility. What are the differences between the microscopic and mesoscopic models of actin-based motility?
What would the mesoscopic model of actin-based motility predict when a non-rigid object, such as a liposome, is coated with ActA? What is experimentally observed? In the AFM experiment, how is the movement of the cantilever detected? What intrinsic property of the cantilever is used to calculate force? Give three examples of keratocyte behavior where history dependent effects may be occurring. Give one example of experimental evidence that supports the mesoscopic elastic gel model and two examples that refute the model. |
