Biol110 Cell Biology
Spring 2009
Section Quiz #5-1
Questions
1) What is the final destination of acid hydrolases missing mannose-6-phosphate sorting
signals?
a) the cell exterior
b) the lysosome
c) the early endosome
d) the late endosome
e) all except a
2) How can cells permanently turn off the signaling by a cell surface receptor at the plasma
membrane?
a) by retrieval through clathrin coated vesicles
b) by sorting into caveolin-coated pits
c) by sorting into multivesicular bodies after internalization
d) by pinching off plasma membrane vesicles and delivering them directly to the lysosome
e) none of the above
3) What is the role of dynamin in clathrin coated vesicle formation?
a) it marks the site for clathrin coated vesicle assembly
b) it is a GAP for the Arf1 GTPase
c) it aids in the separation/scission of the vesicles from the donor membrane
d) it is required for the uncoating of the clathrin coat
e) none of the above
4) How do enzyme-linked cell surface receptors transduce an extracellular signal across the
lipid bilayer of the plasma membrane?
a) they can be ion channels that depolarize the cell
b) they change the structure of their cytoplasmic tails to bind and activate enzymes
c) they can flip-flop the primary messenger into the cell
d) they directly alter gene transcription
e) all of the above
5) Why do activated G-proteins serve as
timing
devices in cell biological signaling events?
