We should perhaps first note that the mechanisms by which organic molecules assemble to become a living organism are far from being understood. In this section, we follow the description of Gilmour and Sephton (2003) and a number of processes that are likely to have been involved in the development of ever more complex molecules.
How can we generate macromolecules from simple organic molecules? The first mechanism is polymerization, which enables monomers to combine, via a chemical reaction that involves the loss of a water molecule. For example, the -OH groups in two sugars may combine with the loss of H2O (Fig. 9.11). It is the same for the -NH2 and -COOH groups in two amino acids. The new molecules may themselves combine to form increasingly complex chains. However, polymerization is the presence of liquid water is difficult, because the water tends to destroy polymers.
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