Which describes the role of nucleation factors for cytoskeletal systems?     cut or sever polymer      typically cap the +ends of polymer      pattern the polymer and reduce the critical concentration for assembly     cross-link pre-existing polymer into higher order structures

Ran is a major player in the process of nucleocytoplasmic transport via the nuclear pore. Because net Ran movement simply follows a concentration gradient, what maintains the Ran gradient across the nuclear membrane? Options:   the concentration levels of cargo in the nucleus to be exported   GTP concentrations in the nucleus   the correct positioning of the GEF and GAP with respect to the nuclear envelope   the interaction of exportin and importin with their cognate substrates   none of the above

arge numbers of ribosomes are present in cells that specialize in producing which molecules?

Describe the role of centrioles in the formation of cilia and flagella.

7) What would happen to the cytoskeleton if you replaced all of the normal ATP in cells with a chemical variant of ATP that behaves in every way like normal ATP except that it cannot be hydrolyzed to ADP? It would prevent actin polymerization.     It would prevent actin depolymerization.     It would NOT affect EITHER polymerization or depolymerization.     It would prevent BOTH polymerization and depolymerization.

Describe one instance when the polarity of microtubules is important in cell function.