Chemical Reactions in Biological Terms - During hydrolysis macromolecules are cleaved into their smaller subunits by adding water. Dehydration synthesis is the linking of smaller subunits by removing water to form larger molecules.
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Let us see how some of these types of reactions affect my meal. Earlier I said that my meal actually consisted of large molecules (often called macromolecules or polymers) of proteins, carbohydrates, and lipids. To change those macromolecules into the types of proteins, carbohydrates, and lipids that my body can use, a set of paired reactions occurs in my cells: hydrolysis and dehydration synthesis (Figure 3.2). Both of these reactions are mediated by enzymes.
The first type of reaction is a degradation reaction called hydrolysis, a term that means water
splitting. In hydrolysis, water molecules are enzymatically added to macromolecules, splitting them into their component subunits. Such small molecules are called monomers.
The second type of reaction is a synthesis reaction called dehydration synthesis. This step recycles the monomers by removing the water used in hydrolysis. The monomers are then joined to form polymers, such as the proteins, carbohydrates, and lipids that my body needs. Hence the name of the process, which means synthesis (or putting together) by dehydration (the removal of water).
So I benefit from my breakfast because of a pair of reactions that are the reverse of each other. One reaction adds water to a macromolecule to degrade it into monomers, and the other process removes water from monomers to form macromolecules. At present I am hydrolyzing, or breaking down, my meal into its component parts, its monomers. Once these simple molecules get into my cells, they will be utilized as sources of energy or as the raw materials used to synthesize the macromolecules that make up me.
So through these two paired reactions, monomers are synthesized into macromolecules that are of biological importance. What are the properties of these biological compounds, and what are their functions? Let us discuss them.
There are four groups of biological compounds that are important in living things: carbohydrates, lipids, proteins, and nucleic acids. Each group is divided into smaller subgroups that play an important role in the chemical activities of living things. (Source: Avila, Vernon L. Biology : Investigating Life On Earth Jones and Bartlett/Bookmark Series in Biology Page 53-54)
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