Chapter 5: Macromolecules/Biomolecules

Introduction

• Focus on organic macromolecules: proteins, carbohydrates, lipids, nucleic acids.
• Importance in diet, health, and the molecular level understanding of these molecules.
• Organic, carbon-based molecules are the building blocks of life.

Structure and Function of Macromolecules

• Macromolecules are large molecules made from smaller units called monomers.
• Monomers (like Legos) form polymers.
• Covalent bonds link monomers into polymers.
• Four classes of macromolecules: proteins, nucleic acids, lipids, carbohydrates.
• Each has distinct monomers and polymers.

Macromolecule Types and Their Monomers

1. Proteins
   • Monomers: Amino acids.
   • Peptide bonds link amino acids.
   • Examples: Enzymes, hormones.
2. Nucleic Acids
   • Monomers: Nucleotides.
   • Phosphodiester bonds link nucleotides.
   • DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).
3. Lipids
   • Not true polymers.
   • Made up of fatty acids and glycerol.
   • Examples: Fats, cholesterol.
4. Carbohydrates
   • Monomers: Monosaccharides.
   • Glycosidic linkages link sugars.
   • Examples: Glucose, sucrose.

Protein Structure

• Levels of Protein Structure
  1. Primary: Sequence of amino acids.
  2. Secondary: Alpha helix and beta-pleated sheets; stabilized by hydrogen bonds.
  3. Tertiary: Overall 3D shape; interactions among R groups.
  4. Quaternary: Multiple polypeptides.
• Folding is crucial; chaperone proteins assist in folding.
• Misfolding can lead to diseases.
• Denaturation: Unraveling of proteins due to environmental changes.

Nucleic Acids

• DNA and RNA
  • DNA: Double-stranded, stores genetic information.
  • RNA: Single-stranded, involved in protein synthesis.
• Components of Nucleotides
  1. Phosphate group.
  2. Pentose sugar (Ribose in RNA, Deoxyribose in DNA).
  3. Nitrogenous base (Purines: Adenine, Guanine; Pyrimidines: Cytosine, Thymine, Uracil).
• Base pairing: A-T (DNA), A-U (RNA), C-G.
• DNA replication is semi-conservative.

Applications and Examples

• Proteins in Biology
  • Hormones, enzymes, antibodies, transport, and structural roles.
• Enzymatic and Defensive Roles
  • Enzymes speed reactions, antibodies fight pathogens.
• DNA's Role
  • Central dogma: DNA -> RNA -> Protein.
• Diseases Related to Misfolding
  • E.g., Sickle cell anemia from single amino acid change.

Summary

• Understanding the molecular structure and function of macromolecules is crucial for comprehending biological processes.
• The interplay between structure and function is a recurring theme in biology.
• Next up: Detailed exploration of lipids and carbohydrates.