Biological Macromolecules and Reactions

Biological Macromolecules * Definition: Large biological molecules, also referred to as macromolecules (macro meaning big or large). * Characteristics: They are very complex and possess unique properties that derive from the specific arrangement of their atoms. For instance, proteins exhibit complex three-dimensional structures with numerous twists, turns, and shapes. * Main Types: * Carbohydrates * Lipids * Proteins * Nucleic Acids ## Terminology of Macromolecules * Polymer: * "Poly" means many. * A long molecule composed of many repeating building blocks. * Examples: Carbohydrates, proteins, nucleic acids, and lipids are all polymers, each made of different types of monomers. * Monomer: * "Mono" means one. * The individual building blocks that link together to form a polymer. * Analogy: Think of a train, where each individual car represents a monomer, and the entire long train (from engine to caboose) constitutes a polymer. ## Building and Breaking Down Polymers * Role of Enzymes: * Enzymes are large molecules that facilitate (speed up) chemical reactions involved in making or breaking down polymers. * Enzymes are also known as catalysts, substances that speed up chemical reactions without being consumed in the process. * Two Key Reaction Types: ### 1. Dehydration Reaction (Synthesis of Polymers) * Purpose: To bind two monomers together, thereby synthesizing (making) a longer polymer. * Mechanism: Involves the loss of a water molecule (H2O). When one monomer contributes a hydroxyl group (—OH) and the other contributes a hydrogen atom (—H), a water molecule is removed, allowing the two monomers to bond. * Illustration: Short polymer (e.g., three monomers) + new monomer {\xrightarrow{\text{- } H2O}} Longer polymer (e.g., four monomers). ### 2. Hydrolysis Reaction (Breakdown of Polymers) * Purpose: To break a polymer apart, disassembling it into shorter polymers or individual monomers. * Mechanism: This is the reverse of a dehydration reaction. It involves the addition of a water molecule (H2O), which breaks the bond between monomers. * "Hydro" refers to water. * "Lysis" means to break apart or break up. * Illustration: Longer polymer + H2O {\xrightarrow{\text{+ } H_2O}} Shorter polymer + separate monomer. * Summary: Dehydration removes water to synthesize a polymer; hydrolysis adds water to break down a polymer. ## Introduction to Carbohydrates * Definition: Carbohydrates are a class of biological molecules that include sugars. They are polymers. * Simplest Form: The simplest carbohydrates are called monosaccharides, also known as simple sugars.