#Question id: 2235
#Unit 2. Cellular Organization
The generation and maintenance of a membrane electric potential requires which of the following:
a. active pumping of ions
b. ion-specific membrane channel proteins
c. ATP
d. a generally permeable membrane
#Question id: 2236
#Unit 2. Cellular Organization
The partition coefficient K, the equilibrium constant for partitioning between oil and water, for butyric acid is about 10–2, and for 1,4-butanediol it is about 10–4. You add liposomes containing only water to a solution with an initial concentration of 1 mM butyric acid and 100 mM 1,4-butanediol outside the liposomes. What is the relative rate of diffusion of the two substances into the liposome interior?
#Question id: 2237
#Unit 2. Cellular Organization
Glucose enters erythrocytes via a GLUT-1 uniporter. As the levels of glucose in the bloodstream decrease between meals, what happens to the glucose in the cells?
#Question id: 2238
#Unit 2. Cellular Organization
Consider the transport of glucose into an erythrocyte by facilitated diffusion. When the glucose concentrations are 5 mM on the outside and 0.1 mM on the inside, the free-energy change for glucose uptake into the cell 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: 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?