In a typical mammalian cell, if the [K⁺]ₒᵤtsᵢdₑ = 5mM and [K⁺]ᵢnsᵢdₑ = 140mM, what is the Nernst potential?
A)+62mV
B)-90mV
C)+90mV
D)-62mV
E)-1.4mV

Question

Quizplus · Accepted Answer

The Nernst equation for potassium is: E = (RT/zF) * ln([K+]outside/[K+]inside) where R is the gas constant, T is the temperature in Kelvin, z is the charge of the ion (+1 for K+), F is Faraday's constant, [K+]outside is the concentration of potassium outside the cell, and [K+]inside is the concentration of potassium inside the cell. Plugging in the values given in the question, we get: E = (RT/zF) * ln(5/140) = -90mV. Therefore, the best choice is B.

In a Typical Mammalian Cell, If the [K⁺]ₒᵤtsᵢdₑ = 5mM