Questions for Neurobiology:

Last update: 9 May 1997
  1. The Nernst equation is written as E=RT/zF lnCo/Ci. Define the terms in this equations.
  2. The Nernst voltage for an ion is also called that ion's 'equilibrium potential'. Why?
  3. Differentiate between conductance and permeability.
  4. Faraday's constant (F) is considered to be 96,500 coulombs mole-1. Where does this number come from?
  5. What is the relationship between resistance and conductance?
  6. In your own words, define capacitance.
  7. What is the effect of capacitance on the time course of the membrane's response to a change in voltage across it?
  8. The Goldman equation for membrane voltage is given as Vm=RT/F ln((pK[K]o + pNa[Na]o)/pK[K]i + pNa[Na]i)). Define the terms. Show that the equation reduces to the Nernst equation if pNa>>pK or pK>>pNa.
  9. Why is the chord conductance equation [i=g(Vm-E)] called chord conductance?
  10. Consider the following I-V graph for a cell with only potassium and sodium channels, and no voltage-gated channels:

    On the figure, draw in the I-V curve for the potassium and sodium currents.

  11. Why is the Na-K ATPase pump called electrogenic?
  12. What are two lines of evidence that refute the current dogma that action potentials arise in the axon hillock (initial segment) of the axon?
  13. Describe the basic molecular architecture of the voltage-gated sodium channel.
  14. On the following axes, draw an action potential. Indicate the following periods:
    1. Sodium channels opening
    2. gNa>gK
    3. Sodium channels inactivating
    4. K channels opening
    5. gK>gNa

  15. What is the effect on conduction velocity of an action potential of increasing the diameter of a neuron? The membrane resistance?
  16. Distinguish between the L, N, and P types of voltage-gated calcium channels.
  17. Explain how one experimentally determines the conductance of a channel.
  18. Distinguish between patch- and whole-cell voltage clamped configurations.
  19. Draw the inactivation and activation curves for a hypothetical voltage-gated channel such as a calcium or sodium channel. Explain what is meant by the terms "voltage-dependent activation" and "voltage-dependent inactivation".
  20. Explain the theorized mechanism of inactivation in shaker-K channels.
  21. Describe the theoretical formation of charged rings by the M2 domains of the nAChR pentameric ionotropic channel. Why is this formation related to the channel's function?
  22. The reversal potential for acetylcholine induced EPSCs is near 0 (about -5mV under physiological conditions). What does this tell you about the selectivity of the nAChR channel?
  23. In what way(s) is the nAChR adapted for the type of response one would like to see at the neuromuscular junction?
  24. How is the GABAA receptor structurally like the nAChR?
  25. Differentiate between the ways barbiturates and benzodiazipines (e.g., Valium) enhance the effect of GABA on the GABAA receptor.
  26. What is the significance of the changing degrees of expression of the NR2A and NR2B subunits of the NMDA-type iGluR with age?
  27. Differentiate between NMDA and non-NMDA iGluRs in terms of the ions they conduct.
  28. How do NMDA and AMPA iGluRs interact at a glutaminergic synapse? Relate this to LTP by tetanic stimulation of the perforant pathway of the hippocampus.
  29. Briefly outline the cycle of a G-protein from its activation by a G-protein-linked receptor to its reconstitution.
  30. What is the common structure seen in virtually all G-protein-linked receptors?
  31. Describe the PIP2 second-messenger pathway. Tell what each of the intermediates do.
  32. Glutamate, via mGluRs, inhibits the M-current (IK,M, or "Muscarine-sensitive potassium current"). How does this make this action of glutamate excitatory?
  33. What is "gustducin"? What sensation does it mediate?
  34. What is the role of cyclic AMP in transducing smells? In adaptation to odors?
  35. What is the "dark current" in the vertebrate photoreceptor? How is it regulated by rhodopsin?
  36. Fill in the following table for subliminal currents:
    Current Ion Carrier Effect on Spike Output
    IA
    ID
    IC
    IAHP
    IM
    INaP
    IT
    IQ
  37. What role is played by the Kv3.1 gene in the maturation of cortical layer IV neurons?
  38. Describe the properties of Ca/CAMKII which make it a likely candidate for involvement in LTP/LTD.
  39. Compare the ways in which cell-wide distribution of synapse-modifying mRNAs (or proteins) versus specific targeting of the mRNA (or protein) could produce long-term information storage at active synapses.
  40. What are Early Immediate Genes, and how are they involved in LTP/LTD?
  41. What do the Drosphila mutants rutabaga and dunce tell us about LTP?