Macromolecules Review

Overview

• This lecture addresses the structure, function, and subunits of macromolecules.
• The key macromolecules discussed are carbohydrates, lipids, proteins, and nucleic acids.

Types of Macromolecules

1. Carbohydrates
   • Empirical Formula: CH₂O
   • Includes monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and polysaccharides (e.g., starch, glycogen).
2. Lipids
   • Includes triglycerides, fatty acids, steroids, phospholipids.
3. Proteins
   • Composed of amino acids.
4. Nucleic Acids
   • Includes nucleotides like DNA and RNA.

Carbohydrates

• Monosaccharides: Basic subunits (e.g., glucose, fructose, galactose).

  • Glucose: 6-carbon sugar, aldohexose.
  • Fructose: 6-carbon sugar, ketohexose, isomer of glucose.
  • Galactose: Stereoisomer of glucose, C4 epimer.

• Disaccharides: Composed of two sugar units (e.g., sucrose, lactose).

• Polysaccharides: Many sugar units (e.g., starch, glycogen, cellulose, chitin).

  • Chitin: Structural material in insects.
  • Cellulose: Structural component in plants.

Proteins

• Amino Acids

  • Monomers of proteins.
  • Polar and nonpolar types (e.g., phenylalanine).
  • Peptide bonds formed through dehydration synthesis.

• Protein Structures

  • Primary: Amino acid sequence.
  • Secondary: Alpha helix and beta-pleated sheets.
  • Tertiary: 3D folding of a single polypeptide chain.
  • Quaternary: Multi-subunit complex (e.g., hemoglobin).

Lipids

• Fatty Acids
  • Saturated (no double bonds) and unsaturated (one or more double bonds).
• Triglycerides
  • Composed of glycerol and three fatty acids.
• Phospholipids
  • Make up cell membranes, composed of glycerol, two fatty acids, and a phosphate group.

Nucleic Acids

• Nucleotides
  • Composed of a phosphate group, ribose sugar, and nitrogenous base.
  • DNA vs. RNA: DNA has deoxyribose and thymine; RNA has ribose and uracil.

Important Concepts

• Enzymes: Proteins that catalyze reactions (ending in -ase).
• Lipids and Water: Generally insoluble due to nonpolar characteristics.
• Macromolecule Functions: Structural roles, energy storage, catalytic functions, information storage.

Additional Points

• Stereochemistry in sugars and amino acids: Importance of spatial arrangement in biological function.
• Role of fatty acids in health: Saturated vs. unsaturated, impact on physical state at room temperature.
• Phospholipid Bilayer: Structure and function, separation of aqueous environments in cells.

These notes summarize key points about macromolecules relevant to students preparing for exams or needing a refresher on biochemical molecules.