Biological Functional Groups and Macromolecules

Overview

This lecture covers the main biological functional groups, their visual identification, and introduces the concepts of monomers, polymers, and the four major macromolecules: carbohydrates, lipids, proteins, and nucleic acids.

Functional Groups: Structure & Visual Identification

• Functional groups are specific clusters of atoms attached to carbon chains that give molecules unique properties.
• The hydroxyl group is an oxygen bonded to a hydrogen (–OH).
• The carbonyl group is a carbon double-bonded to an oxygen (C=O), found at the end or middle of molecules.
• The carboxyl group combines a carbonyl and hydroxyl (–COOH), always at the end of a molecule.
• The amino group contains nitrogen, usually bonded to two or three hydrogens (–NH₂ or –NH₃⁺).
• The sulfhydryl group is a sulfur bonded to a hydrogen (–SH).
• The phosphate group consists of a phosphorus atom double-bonded to one oxygen and single-bonded to three other oxygens.
• The methyl group is a carbon with three hydrogens (–CH₃); discussed in detail later with DNA.

Macromolecules: Monomers, Polymers, and Reactions

• Macromolecules are large biological molecules made from smaller units called monomers.
• Monomers are single units; polymers are chains of monomers.
• The dehydration reaction links monomers by removing water.
• Hydrolysis breaks polymers into monomers by adding water.
• Hydrolytic enzymes catalyze hydrolysis reactions in the digestive system.

Categories of Macromolecules and Their Building Blocks

• Carbohydrates: Monomers are monosaccharides (e.g., glucose, fructose); polymers are polysaccharides (e.g., starch, cellulose).
• Proteins: Monomers are amino acids; polymers are called polypeptide chains.
• Nucleic Acids: Monomers are nucleotides; polymers are polynucleotides.
• Lipids: Do not have typical monomers and polymers; they are grouped by shared characteristics.

Key Terms & Definitions

• Functional Group — Specific group of atoms giving molecules distinct properties.
• Hydroxyl Group (–OH) — Oxygen bonded to hydrogen.
• Carbonyl Group (C=O) — Carbon double-bonded to oxygen.
• Carboxyl Group (–COOH) — Carbonyl and hydroxyl combined.
• Amino Group (–NH₂/–NH₃⁺) — Nitrogen with hydrogens.
• Sulfhydryl Group (–SH) — Sulfur with hydrogen.
• Phosphate Group — Phosphorus bonded to four oxygens.
• Methyl Group (–CH₃) — Carbon with three hydrogens.
• Monomer — Single molecular unit.
• Polymer — Chain of monomers.
• Dehydration Reaction — Removes water to form polymers.
• Hydrolysis — Adds water to break polymers.
• Hydrolytic Enzymes — Enzymes that perform hydrolysis.

Action Items / Next Steps

• Memorize the structures and visual identifiers of the seven functional groups.
• Draw and review the macromolecules chart for monomer/polymer terms.
• Prepare to visually recognize macromolecules as you study each type.