Chapter 4 Lecture

Organic Chemistry as the Foundation of Life

• Definition: Organic chemistry is the study of carbon-containing compounds, essential for understanding the origin of life.

• Organic compounds vary significantly from simple to complex molecules.

Origin of Life

• Milller's Experiment:

  • Stanley Miller conducted significant experiments demonstrating the abiotic (non-biological) synthesis of organic compounds.

  • Suggested that conditions similar to early Earth (e.g., near volcanoes) could create life's building blocks.

• Major elements of life include Carbon (C), Hydrogen (H), Oxygen (O), Nitrogen (N), Sulfur (S), and Phosphorus (P). Their consistent presence across organisms highlights carbon's versatility and foundational role in the diversity of life.

Molecular Diversity through Carbon

• Carbon Bonding:

  • Carbon has a unique ability to form four covalent bonds, leading to diverse organic molecules.

  • The shape of molecules, such as tetrahedral (four single bonds) or planar (double bonds), influences their function.

• Hydrocarbons:

  • Hydrocarbons consist solely of carbon and hydrogen, prevalent in fats and significant energy release upon reactions.

Isomerism and Diversity

• Isomers: Molecules with the same molecular formula but different structures or configurations:

  • Structural Isomers: Differ in covalent arrangements.

  • Cis-trans Isomers: Same covalent bonds but differ in spatial arrangements.

  • Enantiomers: Mirror image isomers important in pharmaceuticals, often with varying biological activities.

Functional Groups and Chemical Properties

• Functional Groups: Specific groups of atoms within molecules that influence chemical properties and reactions:

  • Common Groups:

    • Hydroxyl group (-OH): Alcohols

    • Carbonyl group (C=O): Ketones and aldehydes

    • Carboxyl group (-COOH): Carboxylic acids

    • Amino group (-NH2): Amines

    • Sulfhydryl group (-SH): Thiols

    • Phosphate group (-OPO3): Organic phosphates

    • Methyl group (-CH3): Methylated compounds

• Example: Estradiol and testosterone are both steroids, differing only in their functional groups attached to a common carbon skeleton.

ATP: Energy Currency of the Cell

• Adenosine Triphosphate (ATP):

  • ATP is a crucial organic molecule that acts as an energy source, storing energy in its phosphate bonds.

  • The hydrolysis of ATP releases energy that cells utilize for various functions.