THE CHEMISTRY OF LIFE organic compounds

Chapter Overview: The Chemistry of Life: Organic Compounds

Key Topics

• Organic vs. Inorganic Compounds

  • Organic Compounds: Compounds made of carbon and hydrogen, include carbohydrates, lipids, proteins, and nucleic acids.

  • Inorganic Compounds: Compounds that do not contain both carbon and hydrogen together, e.g., carbon dioxide (CO2), calcium carbonate (CaCO3).

Carbon Atoms and Molecules

• Unique Properties of Carbon:

  • Central component of organic matter.

  • 4 valence electrons allowing for a total of 4 covalent bonds to complete its octet.

  • Strong carbon-to-carbon bonds can be single, double, or triple.

• Hydrocarbons:

  • Organic compounds made only of carbon and hydrogen, can be linear, branched, or ring-shaped.

Isomers

• Definition: Isomers have the same molecular formula but different structural formulas.

  • Structural Isomers: Differ in covalent arrangement of atoms.

  • Geometric Isomers (Cis/Trans): Same covalent bonds with different spatial arrangements.

  • Enantiomers: Mirror images that cannot be superimposed.

Functional Groups and Their Impact on Organic Molecules

• Structural, geometric, and enantiomers influence properties of organic compounds.

• Important Functional Groups:

  1. Hydroxyl Group (-OH): Polar, hydrophilic; increases solubility in water.

  2. Carbonyl Group (C=O): Polar and hydrophilic.

  3. Carboxyl Group (-COOH): Weakly acidic and hydrophilic.

  4. Amino Group (-NH2): Weakly basic and hydrophilic.

  5. Phosphate Group (-PO4H2): Weakly acidic.

  6. Sulfhydryl Group (-SH): Stabilizes protein structure.

Biological Molecules as Polymers

• Biological macromolecules (proteins, nucleic acids) are polymers built from monomers.

• Polymer Formation:

  • Condensation Reaction: Joins monomers, releasing water.

  • Hydrolysis Reaction: Breaks polymers into monomers, adding water.

Carbohydrates

• General Formula: (CH2O)n; consists of carbon, hydrogen, and oxygen.

  • Types of Carbohydrates:

    1. Monosaccharides: Simple sugars (e.g., glucose, fructose).

    2. Disaccharides: Two monosaccharides linked (e.g., sucrose, lactose).

    3. Polysaccharides: Long chains of monosaccharides (e.g., starch, glycogen, cellulose).

• Monosaccharide Examples:

  • Glucose (C6H12O6) exists in ring form in solution.

  • Structural isomers include galactose and fructose.

Polysaccharides

• Energy Storage:

  • Starch: Plant storage form, can be unbranched (amylose) or branched (amylopectin).

  • Glycogen: Animal starch, highly branched, stored in muscles and liver.

• Structural Component:

  • Cellulose: Major component of plant cell walls, cannot be digested by humans due to β-1-4 glycosidic bonds.

Lipids

• Types of Lipids:

  1. Fats (Triglycerides): Made of glycerol and three fatty acids; economical energy storage.

  2. Phospholipids: Cell membrane components; amphipathic nature (hydrophilic head and hydrophobic tails).

  3. Carotenoids and Steroids: Derived from isoprene units; play roles in photosynthesis and regulate cell membrane integrity.

• Fatty Acids:

  • Saturated (solid at room temp) and unsaturated (liquid at room temp); can be monounsaturated or polyunsaturated.

Proteins

• Comprised of amino acids; 20 different types exist.

• Functions of Proteins:

  • Enzymatic, structural, storage, transport, regulatory, motile, and protective proteins.

• Levels of Protein Structure:

  1. Primary Structure: Linear sequence of amino acids.

  2. Secondary Structure: Regular arrangements (alpha helix and beta pleated sheet) stabilized by hydrogen bonding.

  3. Tertiary Structure: Overall 3D shape from side-chain interactions.

  4. Quaternary Structure: Arrangement and interaction of multiple polypeptide chains.

Nucleic Acids

• DNA and RNA are polymers of nucleotides consisting of a sugar, phosphate group, and nitrogenous base.

• Functions:

  • DNA: Genetic blueprint.

  • RNA: Implements protein synthesis and takes part in energy transfers.

Conclusion

• Understanding the chemistry of organic compounds is essential for exploring biological processes and functions.