| SUMMARY: |
Living systems, as defined in biochemical terms (highly organized entities in which each part has a function, where there is a direct relationship between function and structure, capable to extract energy from the environment, capable to replicate and capable to adapt to the environment),1 have a greatly variable chemical
composition depending on species or even on individual, as well as on the environment. The living systems known so far tend to feature certain common structural elements. Thus, even the simplest systems are organized into cells delimited by a membrane. This membrane is formed by a physical
aggregation of lipids. The complex aqueous chemical mixture enclosed inside the membrane is called cytosol. The cytosol typically contains most of the molecules required for survival, growth and cell reproduction. These so-called ‘biomolecules’ tend to belong to a small number of classes, common to all species. In general the most abundant molecule in a cell is water. Its role is essential in living organisms - as solvent, as stabilizing agent for biomolecules, and as a direct participant in essential reactions for cell functioning. |
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