The Chemical Basis of Life II: Organic Molecules

Overview of Organic Molecules

  • Organic molecules contain Carbon and Hydrogen.

  • Major classes: Carbohydrates, Lipids, Proteins, Nucleic acids.

  • Carbon: can form both polar and non polar bonds

Functional Groups

  • Functional groups influence the properties of organic molecules.

    • Amino (-NH2): Basic, polar; found in amino acids.

    • Carbonyl (C=O): Reactive, polar; found in sugars.

    • Carboxyl (-COOH): Acidic; part of amino acids.

    • Hydroxyl (-OH): Polar; found in alcohols.

    • Methyl (-CH3): Nonpolar; influences DNA and proteins.

    • Phosphate (-PO4): Polar, weakly acidic; found in nucleic acids.

    • Sulfhydryl (-SH): Polar; forms disulfide bonds in proteins.

Organic Compounds as Polymers

  • Polymers are made of repeating units (monomers).

  • Formed through dehydration reactions, breaking down via hydrolysis.

  • monosaccharides - polysaccharides

  • amino acid - polypetide or protein

  • nucleotide- nucleic acid

Carbohydrates

  • Structure: Cn(H2O)n

  • Types: Monosaccharides, disaccharides, polysaccharides (e.g., starch, glycogen, cellulose).

  • Monosaccharides: 5 or 6 carbon sugars (e.g., glucose).

  • Bonding: Glycosidic bonds via dehydration; broken by hydrolysis.

Lipids

  • Composed of hydrocarbons; nonpolar and hydrophobic.

  • Types: Fats (triglycerides), phospholipids, steroids, waxes.

  • Fats: Formed from glycerol and fatty acids by dehydration; storage of energy, flavor, and insulation.

  • Types of Fatty Acids: Saturated (solid at RT) and unsaturated (liquid at RT).