Chapter 5: The Structure and Function of Large Biological Molecules

Molecules of Life

All living organisms are composed of four major classes of large biological molecules, each with distinct structures and functions essential for life.

• Carbohydrates

• Lipids

• Proteins

• Nucleic acids

Macromolecules are large, complex molecules formed by the polymerization of smaller subunits called monomers.

The Synthesis and Breakdown of Polymers

Macromolecules are assembled and disassembled through specific chemical reactions that involve water.

• Dehydration reaction: This process joins two monomers together by removing a water molecule, forming a covalent bond. It is essential for the synthesis of polymers.

• Hydrolysis: This process breaks polymers into monomers by adding a water molecule, effectively reversing the dehydration reaction.

These reactions are catalyzed by enzymes, which are specialized macromolecules that accelerate chemical reactions.

The Synthesis of Polymers

Polymer formation and breakdown are fundamental to the structure and function of biological macromolecules.

• Dehydration Reaction: When synthesizing a polymer, a short polymer and an unlinked monomer are joined. The removal of a water molecule forms a new covalent bond, resulting in a longer polymer.

• Enzymes: Enzymes such as polymerases facilitate the dehydration reaction, while hydrolases catalyze hydrolysis.

Example: The formation of polysaccharides, proteins, and nucleic acids all involve dehydration reactions to link monomers into polymers.

Key Equations

• Dehydration Reaction:

• Hydrolysis Reaction:

Additional info: These foundational concepts are critical for understanding the structure and function of carbohydrates, lipids, proteins, and nucleic acids, which will be explored in detail in subsequent sections of the chapter.