Chapter 6 Flashcards
How can membrane potentials be recorded?
Using microelectrodes or voltage-dependent dyes
How are membrane potentials generated?
When there is an ion gradient, a membrane potential will also exist
What is the range for the nernst potential in mammalian cells?
-100 mV to +100 mV
What do currents depend on?
Concentration of the ion on both sides of the membrane, the membrane potential, and the permeability of the membrane to the ion.
What does the membrane potential depend on?
Ionic concentration gradients and the permeability of the membrane to that ion.
How is the membrane potential maintained?
Through the separation of relatively few charges
Is ionic current directly or inversely proportional to electromotive driving force?
Directly proportional (Ohm’s Law)
Capacitive current is directly or inversely proportional to the rate of voltage change?
Directly proportional
How can you measure current across cell membranes?
Through a voltage clamp
How can you record unitary currents through single channels?
Patch-clamp method
How are macroscopic current changes generated?
Through the summation of various single channel currents
What is unique about how channel subunits are arranged?
They are radially symmetrical around a central pore
Describe the makeup of a gap junction
1 gap junction = 2 connexons. 1 connexon = 6 connexins. 1 gap junction = 12 connexins.
What are the subunits of the nicotinic acetylcholine receptor?
2 alpha, 1 beta, 1 gamma, and 1 delta
What is a dendrogram?
An evolutionary tree/pedigree that shows the relatedness between ion channels in different species
