Quiz #3

Question 1

Plasma membrane glycolipids are found?
A. Exclusively in the inner leaflet.
B. Exclusively in the outer leaflet.
C. Equally distributed between the inner and outer leaflets.
D. Only on the basal surface of epithelia.

Answer 1

B. Exclusively in the outer leaflet.

Question 2

Which of the following will not solubilize a typical peripheral membrane protein?
     A. Detergent
     B. Extreme pH.
     C. High salt concentration.
     D. Mildly hypertonic saline.

Answer 2

D. Mildly hypertonic saline.

Question 3

Which of the following are a membrane proteins that do not contain a trans membrane alpha helix?
A. Band 3
B. Glycophorins
C. Glycosylphosphatidylinositol (GPI) - anchored proteins.
D. None of the above.

Answer 3

C. Glycosylphosphatidylinositol (GPI) - anchored proteins.

Question 4

Which statements about ion channels is true?
A. They are opened either by the binding of ligands or by the changes in electric potential across the membrane.
B. They acquire ATP.
C. They are open most of the time.
D. The rate of transport is slow compared to the rate of transport via carrier proteins.

Answer 4

A. They are opened either by the binding of ligand she or by the changes in electric potential across the membrane.

Question 5

Which of the following statements about relative concemntration of Na+ and K+ inside and outside the typical mammalian cell is true?
A. The concentration of Na+ and K+ outiside the cell is about 30 times higher than inside the cell.
B. The concentration of Na+ outside the cell is about 10 times higher than inside the cell, the concentration of K+ inside the cell is 10 to 30 times higher than outside the cell.
C. The concentration is the same for both ions, but there is a Cl- ion concentration gradient across the plasma membrane.
D. The concentration of Na+ inside the cell is 30 times higher outside the cell, the concentration of K+ outside the cell is about 10 times higher that inside the cell.

Answer 5

B. The concentration of Na+ outside the cell is about 10 times higher than inside the cell, the concentration of K+ inside the cell is 10 to 30 times higher than outside the cell.

Question 6

The plasma membrane barrier to passive diffusion is primary a function of the membrane's \_\_\_\_\_\_? 
     A. Phospholipids
     B. Cholesterol
     C. Proteins
     D. Glycoproteins

Answer 6

A. Phopholipids

Question 7

Which of the following lipids are distinctly enriched in lipid rafts?
A. Cholesterol and sphingolipids
B. Glycopilpids and phosphatidylinositol
C. Phosphatidylcholine and sphingomylein
D. Phosphatidylethanolamine and phophatidylserine.

Answer 7

A. Cholesterol and sphingolipids