SBI4U
Hydrolysis and Dehydration Synthesis: Biologically Important Chemical Reactions
Important terms:
 Monomer- single molecule or “building block” that can form polymers
 Polymer- long/large molecule of repeating monomers
 Polymerization- reactions forming a polymer
All chemical reactions within a living organism can be classified as:
 Anabolic reaction- chemical reactions in which simpler substances are combined to form more
complex molecules. Anabolic reactions usually require energy. Anabolic reactions build new molecules
and/or store energy.
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Catabolic reaction- chemical reactions that result in the breakdown of more complex organic
molecules into simpler substances. Release energy that is stored (in ATP) or used to drive anabolic
reactions.
Hydrolysis
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A chemical reaction that results in cleavage of a covalent bond with the addition of a water molecule (Hydro = water; lysis = break);
a reaction process that breaks covalent bonds between monomers by the addition of water molecules.
A hydrogen from the water bonds to one monomer and the hydroxyl bonds to the adjacent monomer.
The covalent bond between these monomers breaks and the larger molecule (polymer) is split into
smaller molecules (monomers)
Releases energy
Dehydration Synthesis
*Note: your textbook describes Dehydration Synthesis as “Condensation”
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A chemical reaction that results in the formation of a covalent bond between two molecules
(“synthesis”) by removing a water molecule (“dehydration”)
One monomer loses a hydroxyl (–OH), and the other monomer loses a hydrogen (–H). (the H usually
comes from a functional group)
Process requires energy.
- Process requires biological catalysts or enzymes.
Each of the four macromolecules (Carbohydrates, Lipids, Proteins and Nucleic Acids) use dehydration synthesis
reactions to build polymers and hydrolysis reactions to break polymers into monomers.