5. lons diffuse across membranes through specific lon channels A) down their chemical gradients. B) down thelr concentra

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5 Lons Diffuse Across Membranes Through Specific Lon Channels A Down Their Chemical Gradients B Down Thelr Concentra 1 (67.28 KiB) Viewed 32 times

5. lons diffuse across membranes through specific lon channels A) down their chemical gradients. B) down thelr concentration gradients. C) down the electrical gradients. D) down their electrochemical gradients. E) down the osmotic potential gradients. 26. The voltage sensor in voltage-gated ion channels is usually comprised of what? a. Protein domains on the extracellular side of the membrane b. Protein domains on the intracellular side of the membrane c Acidic or basic amino acids in a transmembrane domain d. The amino acids that make up the channel pore e. A secondary peripheral membrane protein 37. What are the relative levels of lons in the cytosol compared to outside? (what's Inside a cell) a. High sodium, low potasslum, high calcium b. High sodium, low potassium, low calcium c Low sodium, high potassium, high calcium d. Low sodium, high potassium, low calcium a 18. An action potential causes the release of neurotransmitters at a chemical synapse by what mechanism? a. Causes phosphorylation of the neurotransmitter b. Opens a ligand gated Na channel c. Activates cytoskeletal rearrangement d. Opens a voltage gated calcium channel e. Closes a voltage gated K channel 19. If Nat channels are opened in a cell, how will the membrane potential be affected? (a) The membrane potential is not affected by Nat. (6) It becomes more negative. (c) It becomes more positive. (d) It is permanently reset. 20. Which of the following is a characteristic feature of a uniporter protein in a plasma membrane? A) It is a peripheral membrane protein. B) It exhibits a specificity for a particular type of molecule. C) It requires the expenditure of cellular energy to function. D) it works against diffusion. E) It has few, if any, hydrophobic amino acids. 21. Facilitated diffusion requires A) ATP B) calcium C) a membrane voltage D) lon transport E) membrane proteins