Operation with living cells

The living microbial, animal, or plant cell can be viewed as a chemical plant of microscopic size. It can extract raw materials from its environment and use them to replicate itself as well as to synthesize myriad valuable products that can be stored in the cell or excreted. This microscopic chemical plant contains its own power station, which operates with admirably high efficiency. It also contains its own sophisticated control system, which maintains appropriate balances of mass and energy finxes through the links of its internal reaction network. 

Like the free living single cell, all cells of an organism are equipped with a great number of transport mechanisms. They operate in the cell membranes which separate the cytoplasm from the extracellular space surrounding the cells. These systems denoted as pumps enable the cells to balance their osmotic and ionic composition and to accumulate or eliminate various metabolites. 

Living cells must operate with controls that provide a stable environment and a relatively constant supply of materials needed for biosynthesis and for meeting the energy needs of cells. They must also be responsive to changes in their environment and must be able to undergo mitosis and reproduce when appropriate. 

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