Concise Summary of Lipids

  • LIPIDS

    • Biological molecules, insoluble in water, soluble in nonpolar solvents.
    • Composed of waxy, greasy, or oily compounds in plants and animals.
    • Functions: energy storage, structural components (cell membranes), insulation.

  • Types of Lipids

    • Saponifiable Lipids: Contain esters, can undergo saponification (e.g., triglycerides, phosphoglycerides).
    • Nonsaponifiable Lipids: Do not contain esters, cannot be saponified (e.g., steroids).

  • Fatty Acids

    • Long-chain carboxylic acids ($RCOOH$).
    • Nonpolar tails (hydrophobic) and polar heads (hydrophilic).
    • Characteristics: straight chains; 10-20 carbons; even carbon number; can be saturated or unsaturated.

  • Saturated vs Unsaturated Fatty Acids

    • Saturated: solid at room temperature (e.g., animal fats).
    • Unsaturated: liquid at room temperature (e.g., vegetable oils).
    • Unsaturated fats contain cis-double bonds, creating kinks in the chain, affecting packing and melting points.

  • Triglycerides

    • Composed of three fatty acids and glycerol.
    • Fats: solids at room temp (mostly saturated).
    • Oils: liquids at room temp (mostly unsaturated).

  • Soaps

    • Formed through saponification of triglycerides with strong bases; contain hydrophobic tails and hydrophilic heads, forming micelles.

  • Phosphoglycerides

    • Major components of cell membranes; contain phosphate groups and can be emulsifying agents (e.g., lecithins).

  • Steroids

    • Composed of fused rings; cholesterol is a key component, precursor to bile salts, sex hormones, glucocorticoids.

  • Prostaglandins

    • Involved in numerous body processes, including inflammation and reproduction; inhibited by NSAIDs like aspirin.