A) Microfilaments are composed of globular subunits of the protein actin. In the presence of ATP actin polymerizes to form helical filaments. Briefly describe the role of ATP and how it is necessary for microfilaments assembly.
B) All of the motors known to operate in conjunction with actin filaments are members of the myosin supefamily. Name the two major categories of myosin and their main differences.
C) A cell is treated with a fluorescently labeled antibody against a specific form of myosin. In the fluorescence microscope, the antibody can be seen immediately underlying the cell membrane and associated with some membrane-bound organelles. What kind of myosin is it likely to be? Would this cell be able to carry out cytokinesis in the presence of these antibodies?
