Biological Macromolecules

Overview

• Biological macromolecules are essential for life and are where we get our energy (calories) from.
• Main macromolecules: Carbohydrates, Proteins, Lipids, and Nucleic Acids.
• Functional groups discussed in Chapter 2 are important in determining the properties of macromolecules.

Macromolecules

Carbohydrates

• Functions: Energy source, structural support, and short-term energy storage.
• Components: Carbon, hydrogen, and oxygen (ratio of 1:2:1, e.g., C₆H₁₂O₆ for glucose).
• Types:
  • Monosaccharides: Simple sugars (e.g., glucose).
  • Disaccharides: Two monosaccharides (e.g., sucrose).
  • Polysaccharides: Long chains of monosaccharides (e.g., starch, cellulose).
• Bonds: Glycosidic bonds (covalent bonds in carbohydrates).

Lipids

• Functions: Long-term energy storage, insulation, hormone production, cell membranes.
• Types:
  • Fats and Oils: Made of glycerol and fatty acids.
  • Saturated vs. Unsaturated Fats:
    • Saturated: No double bonds, solid at room temp.
    • Unsaturated: One or more double bonds, liquid at room temp.
  • Trans Fats: Industrially processed unsaturated fats, unhealthy.
  • Omega-3 Fatty Acids: Essential for humans, heart-healthy.
  • Phospholipids: Major component of cell membranes, amphipathic (hydrophilic head, hydrophobic tail).
  • Steroids: Include hormones like testosterone and cholesterol.
• Bonds: Ester linkages.

Proteins

• Functions: Diverse functions including structure, transport, enzymes, etc.
• Structure Levels:
  • Primary: Sequence of amino acids linked by peptide bonds.
  • Secondary: Alpha helices and beta sheets formed by hydrogen bonds.
  • Tertiary: 3D structure formed by various interactions (e.g., disulfide bridges).
  • Quaternary: Multiple polypeptides come together (e.g., hemoglobin).
• Denaturation: Proteins lose structure/function due to changes in environment.

Nucleic Acids

• Types: DNA and RNA.
• Functions: Genetic material, involved in protein synthesis.
• Components: Nucleotides (composed of a nitrogenous base, a sugar, and a phosphate group).
• DNA: Double-stranded, contains genetic information.
• RNA: Single-stranded, involved in protein synthesis.
• Base Pairing: A with T (or U in RNA), C with G.
• Structure:
  • Antiparallel strands.
  • Held together by hydrogen bonds between complementary bases.

Key Concepts

• Dehydration Synthesis: Reaction where water is removed to bond monomers into polymers.
• Hydrolysis: Reaction where water is added to break polymers into monomers.
• Enzymes: Catalysts that facilitate biochemical reactions, mostly proteins.