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Unformatted text preview: 1 continued 1. Which of the following statements ARE CORRECT in describing cell membranes? Cell membranes … (1) are primarily made up of membrane lipids and proteins. (2) define boundaries between the cytosol, organelles, and extracellular environment. (3) transport hydrophobic molecules between compartments in the cell. (4) allow the passive diffusion of ions across the lipid bilayer. (5) regulate the movement of charged molecules between compartments in the cell. a) 1, 3, 4 b) 2, 3, 5 c) 1, 2, 5 d) 1, 2, 3, 4 e) 1, 2, 3, 5 2. What are some of the basic properties of ALL transmembrane proteins? ALL transmembrane proteins ... a) are amphipathic α-helical proteins that span the lipid bilayer. b) are anchored to the cell membrane by a lipid anchor. c) have hydrophobic domains that interact with the aqueous cellular environment. d) have transmembrane domains composed of α-helices or β-sheets spanning the lipid bilayer. e) are glycosylated on the cytosolic side of the cell membrane. 3. What is the importance of the K + Leak channel in generating the membrane potential across animal plasma membranes? a) Excess (+) charges accumulate on the outside of the plasma membrane due to the K + Leak channels transporting K + out of the cell by active transport. b) K + is transported down its electrochemical gradient into the cell by K + Leak channels, leading to excess (+) charges inside. c) When there is a high cytosolic [K + ], the K + Leak channels open and release excess K + out of the cell, leading to excess (+) charges on the outside. d) K + Leak channels use the Na + electrochemical gradient to transport K + to the inside of the cell, leading to excess (+) charges inside. e) K + is passively transported out of the cell through the K + Leak channels, leading to excess (+) charges on the outside. 2 continued 4. A scientist measured the movement of Cl- and NO 3- into a plant vacuole and found that these ions were being transported against their concentration gradients. What is the transport mechanism responsible for this? Cl- and NO 3- are transported by … a) PP i-powered pumps using PP i hydrolysis as the source of energy. b) symporters using the proton motive force. c) Cl- /NO 3- pumps using energy from ATP hydrolysis. d) Cl- and NO 3- channels, driven by the proton motive force. e) antiporters using energy from a H + gradient. 5. Which of the following statements ARE CORRECT in describing how the Na + /glucose symporter transports solutes? (1) Na + and glucose are transported against their electrochemical gradients. (2) Binding of Na + increases the affinity of the symporter for glucose. (3) ATP hydrolysis provides the energy for transport. (4) Na + and glucose are transported into the cytosol....
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This note was uploaded on 03/04/2012 for the course BIOM 426 taught by Professor Staff during the Fall '08 term at WVU.
- Fall '08