Discuss functions of Membrane proteins

Discuss functions of Membrane proteins
58. Cell membranes can maintain a difference in electrical charge between the inte-
rior of the cell and the extracellular fluid. What is this charge difference called?
A. Excitability
B. The membrane potential
C. The action potential
D. The sodium-potassium pump
Answer is B: The inside of a cell is negative, while the exterior side of the mem-
brane is positive. This difference in charge constitutes a difference in electrical
potential (or voltage), known as the resting membrane potential. An action potential
is generated when the membrane is stimulated and the potential reversed.
59. The resting membrane potential of a cell is the consequence of which of the
following concentrations of ions?
A. High K and Cl − outside the cell and high Na and large anions inside the
cell
B. High K and Na outside the cell and high Cl − and large anions inside the
cell
C. High Cl− and Na outside the cell and high K and large cations inside the
cell
D. High Ca 2 and Na outside the cell and high K and large cations inside the
cell
Answer is C: These ionic species are largely responsible for the membrane potential
(cations are negative ions). While there is a higher concentration of Ca outside the
cell than inside, there are fewer Ca than Cl ions.
60. What is one function of mitochondria? To:
A. Produce enzymes to break down molecules
B. Produce molecules of ATP
C. Hold adjacent cells together
D. Allow passage of molecules through the plasma membrane
Answer is B: Mitochondria are organelles within which ATP is made.
61. Membrane proteins perform the following functions EXCEPT one. Which one?
A. Form the glycocalyx
B. Act as receptor proteins
C. Form pores to allow the passage of small solutes
D. Behave as enzymes
Answer is A: The glycocalyx refers to molecules in the plasma membrane that have
a carbohydrate chain attached (prefix “glyco-”).
62. Facilitated diffusion differs from active transport because facilitated diffusion:
A. Requires energy from ATP