Final answer:
The membrane potential of a resting cell is typically -70 mV and is calculated using the Nernst equation, which takes into account the concentration of K+ ions inside and outside the cell. The negative charge inside the cell relative to the outside is maintained by leakage channels and the Na+/K+ pump, which uses ATP to maintain the ion concentration gradient.
Step-by-step explanation:
The membrane potential of a resting cell is typically around -70 mV, which reflects the charge difference across the cell membrane when the cell is not actively firing an action potential. This potential is largely determined by the relative concentrations of ions inside and outside the cell, particularly K+ ions (potassium ions). The Nernst equation can be used to calculate this potential based on these ion concentrations. The inside of a cell has high K+ concentrations compared to the outside, which creates a concentration gradient that allows K+ to diffuse out of the cell, leaving behind a negative charge.
The resting membrane potential is maintained by leakage channels and the Na+/K+ pump, the latter actively transporting Na+ out of the cell and K+ into the cell, using ATP for energy. Since more Na+ ions are pumped out than K+ ions are pumped in, there is a net loss of positive charge inside the cell, contributing to the negative resting membrane potential. While the Nernst equation allows us to calculate an expected membrane potential, the actual measured value can vary depending on cell type and conditions.