17 Questions
What is the formula to calculate channel density?
Single-channel conductance / Macroscopic conductance
In the context of channel density, what does the term 'gating current measurements' refer to?
Measuring the current associated with channel opening and closing
Considering the data provided, which type of channel has the highest conductance?
Mammalian BK potassium channel
What is the lower limit for channel density in excitable cells based on membrane charging during action potentials?
10-15C/μm2
How is the number of channels per unit area estimated in terms of channel density calculations?
Dividing single-channel conductance by surface area
Based on the given data, which type of preparation channel has the highest number per μm^2?
Mammalian BK potassium channel
What is the lower limit of channel density per μm2 based on the information provided?
1 channel
In single channel current measurements, what does 'ip = gp (Vm-Ep)' represent?
The conductance of the channel
What is the significance of the duration of an action potential in relation to ion movement through channels?
It determines the number of ions moved per channel
Which patch clamp configuration involves recording while fixing the membrane potential?
Whole-cell
What does 'stochastic in opening and closing but unitary in amplitude' refer to in single channel currents?
Consistency in the current passing through each ion channel
What is the conductance value calculated for the channel pore with a radius of 0.5nm and a length of 5nm?
63 pS
What is the impact of access resistance on single channel conductance in the example discussed?
Reduces it to 54 pS
How does unequal ion distributions affect the current-voltage relationship in the context of single channel recording?
Results in non-linear I-V relation
What does the slope of an I-V curve represent in the context of single channel current-voltage relation?
Permeability of the channel
What can be inferred about the single potassium channel's conductance when compared with the calculated conductance of the channel pore?
Lower than 63 pS
What happens at around -76mV based on the discussion in single channel current-voltage relation?
Non-linear I-V relation due to unequal ion distributions
Test your knowledge on topics like whole-cell recording, single channel conductance, and channel density measurement in cell biology. Explore concepts such as estimating channel density based on gating current measurements.
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