#Question id: 2438
#Unit 2. Cellular Organization
Rac, a GTPase superfamily protein,
a. is related to Ras.
b. may be activated by growth factors.
c. stimulates lamellipodia formation.
d. stimulates filopodia formation.
e. stimulates stress fiber assembly.
#Question id: 2439
#Unit 2. Cellular Organization
α- and β-tubulin
a. are highly conserved.
b. bind GTP.
c. hydrolyze GTP to GDP.
d. are found in all eukaryotes.
e. are related to the bacterial protein FtsZ.
#Question id: 2440
#Unit 2. Cellular Organization
Microtubule assembly in vitro requires
a. ATP.
b. a threshold (critical) concentration of tubulin.
c. warming the solution to 37°C.
d. microtubule-associated proteins.
e. GTP.
#Question id: 2441
#Unit 2. Cellular Organization
Which of the following statement(s) is (are) true of microtubule assembly?
a. GDP-tubulin normally assembles into microtubules.
b. Microtubule (-) ends grow faster than microtubule (+) ends.
c. Tubulin subunits assemble to form a protofilament.
d. Microtubules consist of multiple protofilaments.
e. Microtubules with a GTP cap will shorten.
#Question id: 2442
#Unit 2. Cellular Organization
The drug colchicine acts to
a. promote microtubule assembly.
b. inhibit microtubule assembly.
c. sever microtubules.
d. block cell division.
e. cap microtubule ends.
#Question id: 2443
#Unit 2. Cellular Organization
Microtubule-associated proteins
a. typically co-localize with microtubules inside cells.
b. are divided into two types: those that stabilize microtubules and those that destabilize microtubules.
c. typically co-purify with microtubules.
d. are similar to α- and β-tubulin.