#Question id: 2239
#Unit 2. Cellular Organization
Consider the transport of K+ from the blood (where its concentration is about 4 mM) into an erythrocyte that contains 150 mM K+. The transmembrane potential is about 60 mV, inside negative relative to outside. The free-energy change for this transport process is: (These values may be of use to you: R = 8.315 J/mol.K; T = 298 K; 9 (Faraday constant) = 96,480 J/V; N = 6.022×10²³ /mol.)
#Question id: 2240
#Unit 2. Cellular Organization
In which of the following cases is energy NOT needed for transmembrane transport?
a. Lysine moves into the cell against its concentration gradient via the Na+/lysine symporter.
b. Potassium ions (K+) move out of the cell down the K+ concentration gradient via potassium channels.
c. Glucose moves into the cell down its concentration gradient via a glucose uniporter.
d. Sodium ions (Na+) move out of the cell down the Na+ concentration gradient via sodium channels.
Which of the following are correct?
#Question id: 2241
#Unit 2. Cellular Organization
Which of the following statement(s) is (are) true of V-class proton pumps?
#Question id: 2242
#Unit 2. Cellular Organization
What two features of the structure of cholesterol make it somewhat amphipathic?
#Question id: 2243
#Unit 2. Cellular Organization
Features of the fluid mosaic model of membrane structure include:
A. a lipid bilayer.
B. dynamic motion of both membrane lipids and proteins.
C. proteins that may either rest on the surface or penetrate the membrane.
D. the hydrophobic core of the bilayer prevents the unassisted movement of water-soluble substances from one side to the other.
E. Covalent interactions between phospholipids, and between phospholipids and proteins, lend strength and resilience to the membrane.
Which of the following is correct?
#Question id: 2244
#Unit 2. Cellular Organization
Arrange the statements below in the proper sequence of events that occur in an action potential:
I. The resting potential is re-established.
II. A stimulus depolarizes the membrane to threshold.
III. Na+ gates open and Na+ rushes into the cell.
IV. K+ gates open and K+ rushes out of the cell.