Use the Following Information When Answering the Corresponding Questions)

question 28

Multiple Choice

Use the following information when answering the corresponding questions) .
The mechanism of cell crawling in protist species is not well defined. The textbook states that pseudopodia extension involves interactions between actin and myosin the same molecules that are involved in mammalian muscle contraction) . However, p the study described below, no one had provided convincing data that actin and myosin were actually involved in cell crawlin protists. Anatomical studies had identified the cytoskeletal protein actin just below the surface of the cell membrane in severa of protist, but physiological studies had failed to show a functional link between actin, myosin, and cell crawling.
In a study by N. Poulsen et al. Diatom gliding is the result of an actin- myosin motility system, Cell Motility and the Cytoskeleto 1999) :23- 22) , researchers tested whether motility in a particular species of diatom involves interactions between actin and myosin.
Figure 27.3
-Cultures of the same species of diatom referred to in the previous question were treated with BDM, a reversible inhibitor of myosin function. Which of the following predictions is consistent with the hypothesis that an
Actin- myosin interaction is necessary for motility?

• A) BDM will not significantly alter motility of the cells in culture.
• B) BDM will significantly decrease motility of the cells in culture.
• C) BDM will significantly increase motility of the cells in culture.