Membrane Transport and Permeability Quiz
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Membrane Transport and Permeability Quiz

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Questions and Answers

What is the main factor that determines the rate of diffusion of a molecule across a membrane?

  • Presence of hydrophobic regions in the molecule
  • Temperature of the surrounding environment
  • Charge of the molecule
  • Size of the molecule and its association with water (correct)

    • What is the resting membrane potential primarily a result of?

  • Presence of negatively charged ions only
  • Active transport and passive diffusion (correct)
  • Concentration gradient of ions
  • Electrochemical gradient only

    • Which ion tends to diffuse out of the cell through potassium channels to reach equilibrium?

  • K+ (correct)
  • Na+
  • Cl-
  • Ca2+

    • What is the electrochemical gradient of a charged solute a combination of?

    <p>Concentration gradient and charge of the solute</p> Signup and view all the answers

    How do proteins associate with the plasma membrane based on their topology?

    <p>Bound by a covalently attached lipid chain</p> Signup and view all the answers

    Which ions result in a difference in electrical charge across the membrane to establish the resting membrane potential?

    <p>[K⁺] and [Na⁺]</p> Signup and view all the answers

    Which factor contributes to making the interior of the cell more negative during resting membrane potential?

    <p>[K⁺] diffusing out through potassium channels</p> Signup and view all the answers

    What type of molecules can easily pass through the lipid bilayer of the cell membrane?

    <p>Nonpolar molecules</p> Signup and view all the answers

    What is the main function of transport proteins in the cell membrane?

    <p>Facilitate the movement of specific molecules across the membrane</p> Signup and view all the answers

    What percentage of all membrane proteins are transport proteins?

    <p>30%</p> Signup and view all the answers

    Why do cells need to transfer molecules and ions across their membranes?

    <p>To maintain homeostasis</p> Signup and view all the answers

    Which part of the cell contains a liquid matrix surrounding organelles?

    <p>Cytosol (ICF)</p> Signup and view all the answers

    What allows cells to maintain different solute concentrations in their cytosol compared to the extracellular fluid?

    <p>Selective permeability of the plasma membrane</p> Signup and view all the answers

    What allows transport proteins in the cell membrane to be specific to certain molecules?

    <p>'Lock-and-key' interactions with molecules</p> Signup and view all the answers

    What is the role of Na+/Ca2+ exchange inhibitors?

    <p>Removing Ca2+ from plasma membranes</p> Signup and view all the answers

    Where is the NCKX2 Na+/Ca2+-K+ exchanger located?

    <p>Neuronal cell membranes</p> Signup and view all the answers

    What cellular mechanisms does the Na+/Ca2+ exchanger (NCX) participate in?

    <p>Exchanging Na+ for Ca2+ across the plasma membrane</p> Signup and view all the answers

    What is the main function of the Na+, K+-ATPase in animal cells?

    <p>Balancing Na+ and K+ concentrations across the plasma membrane</p> Signup and view all the answers

    What are the key roles of NCKX2 Na+/Ca2+-K+ exchanger?

    <p>Influencing synaptic plasticity</p> Signup and view all the answers

    Which organelle is NOT mentioned as a location where Ca2+ can be found in excitable cells?

    <p>Golgi apparatus</p> Signup and view all the answers

    How does the NCKX2 Na+/Ca2+-K+ exchanger contribute to cognitive functions?

    <p>By enhancing Ca2+ clearance in neuronal cells</p> Signup and view all the answers

    What types of sensations can the skin sense?

    <p>Vibration, pressure, stretch, and touch</p> Signup and view all the answers

    How do leak channels differ from gated channels in terms of functionality?

    <p>Gated channels require external stimuli to open</p> Signup and view all the answers

    What is the significance of the selectivity filter in K⁺ channels?

    <p>It dehydrates ions to facilitate their passage</p> Signup and view all the answers

    Where are aquaporins abundant and what is their function there?

    <p>Facilitate osmotic water flow in cells that secrete or reabsorb water</p> Signup and view all the answers

    How many isoforms of aquaporins have been identified in mammalian cells?

    <p>10</p> Signup and view all the answers

    What is the role of Anti-diuretic hormone (ADH) in relation to aquaporins?

    <p>It increases the expression of aquaporins for water reabsorption</p> Signup and view all the answers

    How does Na⁺ size affect its passage through K⁺ channels?

    <p>Na⁺ cannot be accommodated by the filter due to being smaller than K⁺</p> Signup and view all the answers

    What happens to ions as they pass through the selectivity filter of K⁺ channels?

    <p>They dehydrate and interact with carbonyl groups</p> Signup and view all the answers

    In which type of cells are aquaporins predominantly present?

    <p>Cells that secrete or reabsorb high amounts of water</p> Signup and view all the answers

    Which type of membrane transport protein forms pores for specific solute transfer?

    <p>Channels</p> Signup and view all the answers

    In which state of a transporter are the binding sites for solutes exposed to the inside of the cell?

    <p>Inward-open state</p> Signup and view all the answers

    Which type of membrane transporter undergoes a series of conformational changes to transfer solutes across the membrane?

    <p>Carriers</p> Signup and view all the answers

    What type of transport is always passive?

    <p>Transport through channels</p> Signup and view all the answers

    Which type of membrane protein interacts more weakly with solutes compared to transporters?

    <p>Channels</p> Signup and view all the answers

    Mechanosensitive channels convert ____________ stimuli to chemical or electrical signals.

    <p>Mechanical</p> Signup and view all the answers

    Which type of transporter can transfer solutes passively or actively?

    <p>Carriers</p> Signup and view all the answers

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