# Problem: The biochemistry that takes place inside cells depends on various elements, such as sodium, potassium, and calcium, that are dissolved in water as ions. These ions enter cells through narrow pores in the cell membrane known as ion channels. Each ion channel, which is formed from a specialized protein molecule, is selective for one type of ion. Measurements with microelectrodes have shown that a 0.30-nm-diameter potassium ion (K+) channel carries a current of 1.8 pA. a) How many potassium ions pass through if the ion channel opens for 1.0 ms?b) What is the current density in the ion channel?

###### FREE Expert Solution

a)

The number of ions, n:

$\overline{){\mathbf{n}}{\mathbf{=}}\frac{\mathbf{q}}{\mathbf{e}}}$

Charge, q = It

Therefore, n:

$\overline{){\mathbf{n}}{\mathbf{=}}\frac{\mathbf{I}\mathbf{t}}{\mathbf{e}}}$

86% (27 ratings) ###### Problem Details

The biochemistry that takes place inside cells depends on various elements, such as sodium, potassium, and calcium, that are dissolved in water as ions. These ions enter cells through narrow pores in the cell membrane known as ion channels. Each ion channel, which is formed from a specialized protein molecule, is selective for one type of ion. Measurements with microelectrodes have shown that a 0.30-nm-diameter potassium ion (K+) channel carries a current of 1.8 pA.

a) How many potassium ions pass through if the ion channel opens for 1.0 ms?

b) What is the current density in the ion channel?