#Question id: 2234
#Unit 2. Cellular Organization
Which of the following statement(s) is (are) true of transmembrane proteins?
a. All contains a hydrophobic α helix.
b. Some serve as membrane attachment sites for peripheral membrane proteins.
c. Some contain more than one membrane-spanning domain.
d. All are asymmetrically oriented in the lipid bilayer.
#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.)