Introduction to Chapter 5: Macromolecules

Overview of Biologically Relevant Molecules

• Chapter 5 introduces macromolecules: carbohydrates, lipids, proteins, and nucleic acids (DNA and RNA).
• These molecules are categorized as macromolecules for simplicity, though not all are large in size.
• Built on carbon skeletons with attached functional chemical groups, leading to unique properties.

Macromolecules as Polymers

• Many macromolecules are polymers: long molecules made of similar building blocks called monomers.
• Analogy: Monomers are like Lego blocks, and polymers are the structures built from them.
• Three of the four classes are true polymers:
  • Carbohydrates
  • Proteins
  • Nucleic acids
• Lipids are not built as true polymers.

Role of Enzymes

• Enzymes act as catalysts to speed up chemical reactions necessary for building or breaking polymers.
• These reactions are essential for macromolecule synthesis and degradation.

Chemical Reactions in Polymer Synthesis

• Dehydration Synthesis: Links monomers by losing a water molecule.
  • Forms covalent bonds by removing a hydrogen and hydroxide to create water.
• Hydrolysis: Breaks polymers into monomers by adding water.
  • Water is added to break bonds, separating hydrogen and hydroxyl group.

Diversity and Variability in Macromolecules

• Cells contain thousands of different macromolecules, contributing to diversity.
• Variation in macromolecules exists among:
  • Different cells in multicellular organisms (e.g., skin vs. muscle cells).
  • Individuals within the same species.
  • Different species.
• A small set of monomers can create vast variations in polymers (e.g., DNA has four building blocks).

This foundational understanding of macromolecules sets the stage for exploring their complex roles and functions in biological systems.