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A type of vacuum pump. The ion pump consists of two parallel plates with strong opposite electrical charges, which generates a strong electric field in between them. Any particles which happen to be in between become ionized and stick to one plate or the other, the end result being that the number of particles floating around, and thus the overall pressure, decreases. This pump is often used to achieve ultra-high vacuum.

In biochemistry, an ion pump is a protein embedded in a membrane that...well...does exactly what it says on the tin. Water soluble ions (such as sodium or even silver) are selectively transported across the otherwise impermeable membrane or against a concentration gradient. This has a number of uses, such as transforming energy from a gradient to ATP (the proton pump) or maintaining a physiological concentration of some ion.

For example, calcium is a common "messenger" in the cell whose concentration is carefully regulated. Pumps in various membranes (the plasma membrane and the mitochondrial membrane) are 'switched' on or off to kick start a 'calcium wave' that sweeps across the cell. Indeed, the whole process of neuron's transmitting information is based on altering the concentration of two ions (sodium and potassium) across the cells outer membrane. The charge difference is what is transmitted, which is controlled by the ion pumps.

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