Chemical selection of elements by cells

The selection of the chemical elements by a particular cell from the environment involves a series of steps, the complexity of which depends upon the organism, There are usually two membranes to be crossed (bacteria) but there may be as many as ten (higher animals which distribute elements from intake fluid, through cells of organs to circulating fluids through a further set of cells to fixed locations in particular parts of space). The individual steps can be thermodynamically controlled or kinetically managed. In the second case energy can be used. The elements may remain in relatively fast exchange in their final condition or in non-exchanging chemical combination. The variety of paths which individual elements follow in any organism adds to the specific character of the organism. Clearly the paths have evolved to create an element distribution which we shall call thr metallome. to parallel the nomenclature of protein distribution, the proteome, (C) 2001 Elsevier Science B.V. All rights reserved.