BG2110 Bioelectricity Topic 6: Channel Gating Quiz
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Questions and Answers

What is the probability of a single channel being opened under steady-state conditions?

  • Po (correct)
  • No
  • N
  • Nc

    • What must be the sum of the probabilities of a channel being open and closed?

  • Pc
  • N
  • 1 (correct)
  • No

    • Which distribution describes the probability of exactly No channels being opened for N channels?

  • $BN(N_o) = Pc^o (1 - Pc)^{N-N_o}$
  • $BN(N_o) = Po^o (1 - Po)^{N-N_o}$ (correct)
  • $BN(N_o) = Po + Pc$
  • $BN(N_o) = N!N$

    • What does Pc represent in the context of channel gating statistics?

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

    In channel gating statistics, what is the condition for the probability of a channel being open or closed?

    <p>$Po + Pc = 1$</p> Signup and view all the answers

    What type of current is elicited by depolarization from rest?

    <p>Outward &quot;on&quot; Ig</p> Signup and view all the answers

    What current is associated with repolarization?

    <p>Inward &quot;off&quot; Ig</p> Signup and view all the answers

    At what voltage is the charge movement integral of gating current (Q) 20nC?

    <p>-120mV</p> Signup and view all the answers

    What does the voltage dependence of the charge movement allow estimation of?

    <p>The total number of channels in the cell</p> Signup and view all the answers

    According to Boltzman equation, what does the ratio of open to closed channels depend on?

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

    What is responsible for revealing the voltage-dependence of the channel?

    <p>Gating current</p> Signup and view all the answers

    What does the symbol 'C' represent in the context of channel gating kinetics?

    <p>Closed state of a channel</p> Signup and view all the answers

    Which formula is used to calculate the open probability of a channel?

    <p>Po = α / (α + β)</p> Signup and view all the answers

    What does the average dwell time for the channel remaining in the open state represent?

    <p>Time spent in the open state before transitioning</p> Signup and view all the answers

    In the context of channel gating kinetics, what is the probability density function for the dwell time at the closed state based on?

    <p>An exponential distribution</p> Signup and view all the answers

    What information can be obtained from fitting dwell time histograms in channel gating kinetics?

    <p>Rate constants α and β</p> Signup and view all the answers

    Which formula is used to calculate the closed probability of a channel?

    <p>Pc = β / (α + β)</p> Signup and view all the answers

    What is the term used to describe the binary nature of channel gating, where channels exist either in conducting (open) or non-conducting (close or inactivated) state?

    <p>Stochastic gating</p> Signup and view all the answers

    Which type of channels open in response to ligand-binding, mechanical stimulus, and changes in membrane potential?

    <p>Stretch-sensitive channels</p> Signup and view all the answers

    What is the term used to describe the loss of channel conductance after activation, even when the activation stimulus is still present?

    <p>Stochastic inactivation</p> Signup and view all the answers

    What type of channels are constitutively open and do not require a specific stimulus for their opening?

    <p>Leak channels</p> Signup and view all the answers

    How do voltage-gated channels respond to changes in membrane potential?

    <p>By altering their conformation</p> Signup and view all the answers

    What attracts the positively charged segment of a voltage-gated channel to the negative interior of the cell?

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

    What is the formula for the mean number of open channels?

    <p>No = NPo</p> Signup and view all the answers

    How does the variance in the number of open channels relate to the fluctuation in macroscopic channel current?

    <p>They are directly proportional</p> Signup and view all the answers

    What does the mean macroscopic current formula represent?

    <p>Current per channel</p> Signup and view all the answers

    Which factor influences the 'noise' in channel properties analysis?

    <p>Increase in random openings/closings</p> Signup and view all the answers

    What does the point amplitude histogram help analyze?

    <p>Fluctuations in macroscopic current</p> Signup and view all the answers

    In the point amplitude histogram, what do the peaks represent?

    <p>'Noise' amplitude</p> Signup and view all the answers

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