Question

Choose the statement that is most correct about membrane potential.

1) Voltage would be measured by placing two electrodes on the exterior of the axon.
2) Voltage would be measured by placing one electrode inside the membrane and another outside the membrane.
3) Voltage would be measured by placing one electrode on one end of the axon and another electrode on the other end.
4) Voltage would be measured by placing one electrode on the axon and grounding the other electrode.

Answer 1

Membrane potential is best measured by inserting one electrode into the cell and placing another outside. The correct answer is option 2).

Step-by-step explanation:

The membrane potential of a cell can best be measured by option 2, which states: "Voltage would be measured by placing one electrode inside the membrane and another outside the membrane." This is because the membrane potential is defined as the electric potential difference across the cell's plasma membrane.

Physiologically, the typical membrane potential in neurons is around -70 mV to -90 mV, with the inside of the cell being negative relative to the outside. The electrode inside the cell is often called the recording electrode, while the one placed outside is known as the reference electrode.

By measuring the charge difference between these two points, scientists can determine the transmembrane voltage, which is crucial for functions such as the conduction of electrical impulses along nerve cells. The separation of charges leads to an electric field that has significant effects on the membrane structure and its permeability to ions.