Lecture: Introduction to Biological Macromolecules and Organic Chemistry

Overview of Solutions

• Solution: A homogeneous mixture combining a solute and a solvent.
  • Solute: Substance that gets dissolved, usually solid.
  • Solvent: Liquid that dissolves the solute.
• Aqueous Solution (aq): Water is the solvent, capable of dissolving polar or charged solutes due to its polarity.
  • Example: Table salt dissolves in water.
  • Water's ability to dissolve ionic and polar covalent molecules stems from its attraction to their charges.
• Polarity and Solubility:
  • "Like dissolves like"; nonpolar molecules do not dissolve in water (e.g., oils).

Introduction to Organic Compounds

• Carbon-Based Life:
  • Life is predominantly carbon-based, with carbon bonded to elements like hydrogen.
  • Organic vs Inorganic: Organic compounds have carbon-hydrogen bonds.
• Importance of Carbon:
  • Carbon has four valence electrons, forming four covalent bonds.
  • Vital in forming complex organic molecules due to versatile bonding capabilities.
• Hydrocarbons:
  • Composed of carbon and hydrogen, can form chains of various lengths.
  • Examples include methane, ethane, propane, and octane.

Structural Formulas and Isomers

• Structural Representations:
  • Methane (CH4) forms a tetrahedral shape.
  • Hydrocarbons can be unbranched or branched (e.g., butane and isobutane).
  • Can form rings like cyclohexane and benzene.
• Isomers:
  • Compounds with the same formula but different structures.
  • Example: Butane vs. Isobutane.

Functional Groups

• Functional Group Overview:
  • Determine chemical behavior of organic molecules.
  • Include groups like hydroxyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl.
• Examples:
  • Hydroxyl (OH): Polar, forms hydrogen bonds, soluble in water (hydrophilic).
  • Carbonyl (C=O): Aldehydes and ketones, site for reactions.
  • Carboxyl (COOH): Acts as an acid, can lose a proton.
  • Amino (NH2): Acts as a base, can gain a proton.
  • Phosphate (PO4): Carries negative charge, stores energy (e.g., ATP).
  • Sulfhydryl (SH): Forms disulfide bonds, important for protein structure.

Miller-Urey Experiment

• Objective: Simulate early Earth conditions to test the hypothesis of life emerging from non-living chemistry.
• Setup: Simulated water cycle with ancient atmospheric gases and energy sources (e.g., lightning).
• Findings: Produced amino acids, showing that life's basic building blocks could form under prebiotic conditions.
• Significance:
  • Demonstrated biomolecules could form naturally without life.
  • Paved way for prebiotic chemistry as a field of study.
  • Suggests life’s building blocks might form throughout the universe.