Toronto Metropolitan University

BLG 311

Quiz 4 (Section 3) Membrane structure
1. Which of the following phospholipids has a headgroup with an overall (net) negative charge?
(A) phosphatidylethanolamine
(B) phosphatidylcholine
(C) phosphatidylinositol
(D) phosphatidylglycerol
(E) phosphatidylserine
2. Which of the following are NOT features of the lipid bilayer that makes up the plasma
membrane?
(A) The plasma membrane has more cholesterol content than is typically found in the lipid
bilayer of other organelles (e.g. the endoplasmic reticulum).
(B) There is asymmetry in the content of specific phospholipids in each leaflet of the lipid
bilayer of the plasma membrane.
(C) The plasma membrane has little or no membrane proteins, as these are always found in other
organelles like the Golgi or the Lysosome.
(D) The plasma membrane is less permeable to water than the membrane of other organelles.
(E) The plasma membrane is a sealed compartment, such that the hydrophobic inner core of the
lipid bilayer is not exposed to the aqueous environment found on either side of the membrane.
3. Which of the following about lipid rafts is FALSE? Lipid rafts
(A) are small regions of the membrane with lipids that pack together better (more closely) than
the rest of the lipids in the bilayer.
(B) contain phospholipids with fatty acids that tend to be enriched in saturated hydrocarbon
chains
(C) are enriched in cholesterol
(D) are slightly thicker than regions of the membrane that surrounds the lipid rafts.
(E) none of the above (all of the above statements are true).