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Ion Channels
Dreaded Exam Questions
1. Write Ohm’s Law in a form that gives chord conductance.
2. Write the equation for capacitive current
3. What is the typical capacitance of a cell membrane.
I
4. Which of the following I-V curves rectifies and which is
ohmic?
b
a
V
5. What is the theoretical limit for a single channel
conductance?
6. What implication about the permeation process can be deduced from a relationship between
single channel conductance and concentration that can be fit with the following equation (similar
to the Michaelis Menten equation):  
 max
1
KM
[S ]
7. What is the name of the following equation that predicts open-channel rectification:
 EzF
)
Ez 2 F 2 [ S ]i  [ S ]o exp(
RT
I S  PS
RT
1  exp(  EzF
)
RT
.
8. What is the name of the gating process that, during a maintained depolarization: (a) causes a
sigmoidal turn on and exponential turn off of conductance in a Na or K channel, and (b) causes
an exponential turn off of conductance in a Na or shaker K channel?
9. What portion of the molecule of a voltage gated channel forms: (a) the selectivity filter, (b) the
voltage sensor, (c) the inactivation gate?
10. What is the name of the outward current that is produced by the outward, rotational
movement of S4 during activation?
11. How is gating accomplished in the nAChR?
.
12. How many subunits make up the pore-forming structure in K, Na/Ca, nAChR, glu channels
and how many membrane spanning segments are there in a subunit?
13. What is use-dependent block?
14. What effect does Mg2+ have on open-channel conductance of the NMDAR?
15. What channels are blocked by: TTX, Nifedipine, 4-AP, QX 314, Iberotoxin, ω-Conotoxin,
TEA?