Question

how are ionic gradients and electric potentials maintained across the plasma membrane

Answer 1

Magnitude of an electric potential in all cell is 70mV, cytoplasmic face of the cell is negative as compared to the exoplasmic face. The ionic gradient and electric potential across the membrane perform an important role in different biological process like uptake of molecules and amino cids, electric signal of nerve cell depends on the closing and opening of ion channel with the change in membrane electric potential. outward flow of K+ ions through K+ channel determine the change in rasting potential of membrane. Plasma membrane of animal cell contains open K+ channel along with few Na+, Cl- or Ca2+ pen channel. the result of outward movement of K+ ion assisted by the K+ concentration gradient is that, leaving a negative charge inside the membrane and positive charge outside the membrne. uneven distribution of ions across the membrane determines the membrane resting potentials. the concentration of K+ ion is higher insisde the cell and Na+ and Cl- concentration is more outside the membrane maintains stable concentration gradient across the membrane. As K+ ions begin to move outside the membrane, interior of the cell start losing positive charge and after some time outside the membrane get positively charged and inside membrane get negatively charged, this create difference in electrical potential across the cell membrane. This difference in electrical potential results in the electrical force that drive K+ back into the cell. therefore, the difference in electrical potential across the membrane balances the ionic concentration gradient is called equilibrium potential.