MAP 2 Flashcards
Which of the following is NOT an integral membrane protein?
A. actin
B. occludins
C. carrier proteins for mediated transport
D. connexons
E. channels for ion diffusion across membranes
A. actin
A primary active transport process is one in which __________.
A. the plasma membrane folds inward to form a vesicle containing extracellular material
B. molecules pass directly through the phospholipid bilayer of the plasma membrane
C. molecules move through transport proteins that have been activated by ATP
D. an intracellular vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid
E. molecules move across the plasma membrane without an input of energy
C. molecules move through transport proteins that have been activated by ATP
Primary active transporters, such as the sodium-potassium ATPase (or pump), are activated when ATP is hydrolyzed. This activation allows for the transport of solutes across the plasma membrane against concentration gradients.
Some transport processes use transport proteins in the plasma membrane, but do not require ATP. This type of transport is known as _____.
A. simple diffusion B. facilitated diffusion C. endocytosis D. exocytosis E. active transport
B. facilitated diffusion
Facilitated diffusion is a passive transport process during which molecules move down their concentration gradients through transport proteins.
The majority of water molecules moving across plasma membranes by osmosis do so via a process that is most similar to ____.
A. facilitated diffusion B. active transport C. a process that requires energy from the cell D. simple diffusion E. cotransport
A. facilitated diffusion
The sodium-potassium pump uses ATP to move sodium and potassium ions across the plasma membrane. This statement describes _____.
A. primary active transport B. exocytosis C. secondary active transport D. facilitated diffusion E. simple diffusion
A. primary active transport
The sodium-potassium pump is activated by ATP. This activation allows the pump to transport sodium and potassium ions against their gradients.
A vesicle fuses with the plasma membrane and releases its contents to the extracellular fluid. This statement describes _____.
A. simple diffusion B. active transport C. facilitated diffusion D. endocytosis E. exocytosis
E. exocytosis
The term exocytosis literally means “out of the cell.”
If the equilibrium potential for K+ is -94mV, the Vm of a cell is -70mV, and K+ is more concentrated inside the cell, which of the following statements is true?
A. The inside of the cell has enough negative charge to prevent the outward movement of K+ and there will be no net movement of K+ across the membrane.
B. The inside of the cell has more than enough negative charge to prevent the outward movement of K+, and K+ will be drawn into the cell.
C. The inside of the cell does not have enough negative charge to prevent the outward movement of K+, and K+ will leave the cell under these conditions.
D. Since the Vm potential is normal, this means that there is no net movement of ions across the membrane.
C. The inside of the cell does not have enough negative charge to prevent the outward movement of K+, and K+ will leave the cell under these conditions.
Since the equilibrium potential is -94mV, that means that there needs to be more negative charge inside the cell than -70mV to prevent the chemical driving force from pushing K+ out of the cell. In order to get K+ to move into the cell, the Vm would need to be even more negative than -94mV.
Since the equilibrium potential is -94mV, that means that there needs to be more negative charge inside the cell than -70mV to prevent the chemical driving force from pushing K+ out of the cell.
If a 300 mOsm cell (10 mOsm of which are from the membrane-permeable molecule urea) is placed into 300 mOsm solution containing no urea, what will happen to the cell?
If a 300 mOsm cell (10 mOsm of which are from the membrane permeable molecule urea) is placed into 300 mOsm solution containing no urea, what will happen to the cell?
A. shrink (shrivel) B. increased turgor C. swell D. burst E. no change
A. shrink (shrivel)
If a 300 mOsm cell, of which 10 mOsm are from the membrane permeable molecule urea is placed into 300 mOsm solution containing no urea, the urea moves out of the cell down its concentration gradient. As a result, some water also moves out of the cell, so the cell shrinks.
In active transport, the transporter has equal affinity for the molecule being transported on both sides of the membrane.
False
What is the meaning of carrier proteins and pumps becoming saturated?
These transporters have reached a maximal net flux, beyond which further increases in concentration no longer affect their rate.
Molecules with a relatively high lipid solubility are capable of crossing the membrane
A. directly through the lipid bilayer.
B. only through specific protein channels.
C. only with the addition of energy.
D. indirectly by moving across a carrier protein.
E. through specific lipid channels.
A. directly through the lipid bilayer.
Which of the following will NOT increase the net flux of an ion across a membrane?
A. elevated permeability of the membrane
B. reduced surface area
C. increased concentration gradient across the membrane
D. more channels for that ion in the membrane
E. enhanced surface area
B. reduced surface area
Oxygen diffuses from blood into cells down its concentration gradient. As cells become more active and oxidative phosphorylation increases in the cell, which of the following occurs?
A. The concentration gradient for oxygen and its rate of movement into the cell do not change.
B. The concentration gradient for oxygen decreases and oxygen movement into the cell decreases.
C. The concentration gradient for oxygen increases and oxygen movement into the cell increases.
D. The concentration gradient for oxygen decreases and oxygen movement into the cell increases.
E. The concentration gradient for oxygen increases and oxygen movement into the cell decreases.
C. The concentration gradient for oxygen increases and oxygen movement into the cell increases.
The unequal distribution of charge in solutions on either side of a membrane will lead to a ________ of charge across the membrane and a ________ of counter ions in a region close to the membrane.
A. collection : clustering B. separation : restriction C. separation : clustering D. buildup : restriction E. collection : restriction
C. separation : clustering
Which ion(s) would have a positive equilibrium potential? (Assume a resting membrane potential (Vm) of -70mV.)
A. both X+ and B- ions
B. A-, whose [ECF] is100 mM and [ICF] is 100 mM
C. X+, whose [ECF] is120 mM and [ICF] is 30 mM
D. B-, whose [ECF] is140 mM and [ICF] is30 mM
E. X+ , A- , and B- ions
C. X+, whose [ECF] is120 mM and [ICF] is 30 mM
