http://getbooksolutions.com
Link full download: https://getbooksolutions.com/download/test-bank-for–
molecular-biology-of–the-cell-5th-edition-by-alberts
Test Bank for Molecular Biology of The Cell 5th edition by Alberts
Chapter 10:Membrane Structure
Questions
10-1 You are interested in studying the composition of lipid bilayers and how
they are maintained. You discover two uncharacterized phospholipids, which you
call PLX and PLZ. You decide to characterize the behavior of PLX and PLZ by labeling
the head group of each phospholipid. This label is stable when the lipid resides in
the membrane’s outer leaflet but unstable when the lipid resides in the membrane’s
inner leaflet. You incorporate labeled versions of PLX and PLZ into either the inside
or the outside of the cell, and monitor the change in signal intensity of these lipids in
the plasma membrane. Your data are presented in the graphs in Figure Q10–1.
Figure Q10-1
1. Where in the plasma membrane are PLX and PLZ normally located?
2. Are there flippases in the cell for either of these phospholipids? Why?
10-2 You are interested in studying lipid rafts. You have devised a method to
create an artificial lipid bilayer that contains small patches of lipids that are
straighter and longer than those found in the rest of the bilayer. How would you
expect the fluidity of these small patches to compare with the rest of the lipid
bilayer? Explain.
10-3 It is thought that excess lipids in the cell are packaged into lipid droplets in
the endoplasmic reticulum. Explain why lipid droplets are surrounded by a
http://getbooksolutions.com
phospholipid monolayer and not a phospholipid bilayer, like other vesicles that bud
from the endoplasmic reticulum.
10-4 Your friend has isolated plasma membranes and reassembled the
membranes into small vesicles. Using fluorescently labeled lectin, he sees that some
of his vesicles are fluorescently labeled and some are not. Recall that lectin binds to
carbohydrates. Furthermore, his labeled lectin cannot permeate membranes.
1. Which population of vesicles has a surface similar to that of the cell? Why?
2. How do you explain the other population of vesicles?
10-5 Your friend is working on a protein that he calls p125, because of its
molecular mass. He knows that p125 is a transmembrane protein with three
membrane-spanning domains. It has been previously reported that p125 interacts
with three proteins called p175, p80, and p50 (again, on the basis of their apparent
