More generally, however, it is used to characterize the inclined tendency of solutes to simply diffuse across a membrane, a process involving no chemical transformation. In biology, the term is sometimes used in the context of a chemical reaction, in particular to describe the energy source for the chemical synthesis of ATP. In instances pertaining specifically to the movement of electrically charged solutes, the potential is often expressed in units of volts. The maximum voltage that a battery reaction can produce is sometimes called the standard electrochemical potential of that reaction (see also electrode potential and Table of standard electrode potentials). In a battery, an electrochemical potential arising from the movement of ions balances the reaction energy of the electrodes. The term is typically applied in contexts where a chemical reaction is to take place, such as one involving the transfer of an electron at a battery electrode. Similarly chemical energy in cells can be used to create electrochemical gradients. Alternatively, energy can be used to pump water up into the lake above the dam. Membrane transport proteins such as the sodium-potassium pump within the membrane are equivalent to turbines that convert the waters potential energy to other forms of physical or chemical energy, and the ions that pass through the membrane are equivalent to water that is now found at the bottom of the dam. The combination of these two factors determines the thermodynamically favourable direction for an ion's movement across a membrane.Įlectrochemical gradients are analogous to hydroelectric dams and equivalent to the water pressure across the dam. Second, a chemical component is caused by a differential concentration of ions across the membrane. First, the electrical component is caused by a charge difference across the lipid membrane. This potential energy is used for the synthesis of ATP by oxidative phosphorylation.Īn electrochemical gradient has two components. In mitochondria and chloroplasts, proton gradients are used to generate a chemiosmotic potential that is also known as a proton motive force. In biological processes the direction an ion will move by diffusion or active transport across membrane is determined by the electrochemical gradient. It represents one of the many interchangeable forms of potential energy through which energy may be conserved. Electrochemical potential is important in electroanalytical chemistry and industrial applications such as batteries and fuel cells.
0 Comments
Leave a Reply. |