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Ion Channels and Membrane Potential quiz #1

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  • What are ion channels, and how do they achieve selectivity for specific ions?
    Ion channels are transmembrane proteins that facilitate passive transport of small polar molecules, such as ions, across the cell membrane. They achieve selectivity through a selectivity filter within the channel, which only allows specific ions to pass by disassociating them from water, ensuring that only the targeted ion can move through the channel.
  • What is resting membrane potential, and what factors contribute to its establishment in cells?
    Resting membrane potential is the state where the movement of positive and negative ions across the cell membrane is balanced, even though the overall charge on each side may differ. It is established by the sodium-potassium pump, which creates concentration gradients, and potassium leak channels, which allow potassium to flow and help restore or maintain the membrane potential.
  • How does the patch clamp technique help scientists study ion channels?
    The patch clamp technique allows scientists to measure the activity of individual ion channels by isolating a single channel with a micropipette. This technique monitors the flow of ions in and out of the channel, providing detailed information about the function and behavior of specific ion channels in the cell membrane.
  • What are the three main types of gating mechanisms found in ion channels?
    The three main types are voltage-gated, ligand-gated, and mechanically-gated ion channels. Each opens in response to changes in membrane charge, ligand binding, or mechanical force, respectively.
  • How do ion channels achieve selectivity for specific ions?
    Ion channels have a selectivity filter that only allows specific ions to pass by disassociating them from water. This filter is structured to only permit the targeted ion to cross the channel.
  • What does 'resting membrane potential' mean in the context of cell membranes?
    Resting membrane potential refers to the state where the movement of positive and negative ions across the membrane is balanced. It does not mean equal charge on both sides, but rather equal rates of ion movement.
  • Which two key components help establish and maintain the resting membrane potential in cells?
    The sodium-potassium pump and potassium leak channels are key components. The pump creates concentration gradients, while the leak channels allow potassium to flow and help restore membrane potential.
  • What does the Nernst equation calculate in relation to membrane potential?
    The Nernst equation calculates the difference in concentration and charge of ions across the membrane. It helps determine the membrane potential for specific ions.
  • How does the patch clamp technique allow scientists to study ion channels?
    The patch clamp technique uses a micropipette to isolate a single ion channel and measure the flow of ions through it. This provides detailed information about the function and behavior of individual ion channels.
  • Why are ion channels considered to facilitate passive transport?
    Ion channels allow ions to move across the membrane without the use of cellular energy, following their concentration and charge gradients. This movement is called passive transport.
  • What does a negative cell voltage indicate in the context of membrane potential?
    A negative cell voltage means that the inside of the cell is more negatively charged compared to the outside. This reflects a difference in charge across the cell membrane, with more negative ions or fewer positive ions inside relative to the extracellular environment.