In-Depth Notes on Triglycerides and Fatty Acids

  • Introduction to Triglycerides

    • Triglycerides are a key category of lipids, primarily known as fats and oils.
    • Examples of fats include butter, margarine, and shortening.
    • Examples of oils include olive oil and canola oil.

  • Structure of Triglycerides

    • Schematic representation includes:
    • Glycerol backbone
    • Three fatty acids attached via ester groups
    • Actual structure has:
    • Glycerol backbone
    • Three long-chain hydrocarbon fatty acids, which may contain double bonds.
    • Upon breakdown of triglycerides, results are glycerol and three free fatty acids.

  • Fatty Acids

    • Fatty acids attached to glycerol can vary; they are not necessarily identical.
    • Fatty acids are termed acids as they are carboxylic acids.
    • Line-angle structures:
    • Each bend/corner denotes a carbon atom.
    • The presence of -COOH group indicates it's a carboxylic acid.
    • Variability of fatty acids includes:
    • Hydrocarbon chains with all single bonds
    • Hydrocarbon chains with double bonds
    • Variations in chain length (different types of fats and oils).

  • Notation for Fatty Acids

    • Fatty acids are denoted by a notation pattern: number: number
    • First number = number of carbons
    • Second number = number of double bonds
    • Types of fatty acids:
    1. Saturated fatty acids: No double bonds
    2. Monounsaturated fatty acids: One double bond
    3. Polyunsaturated fatty acids: More than one double bond.
    • Example usages:
    • Saturated fatty acid with 12 carbons and 0 double bonds (written as 12:0).
    • Monounsaturated fatty acid example has 1 double bond (e.g., 14:1).
    • Polyunsaturated fatty acids vary widely in double bond count (e.g., 18:3).

  • Omega Notation in Fatty Acids

    • Terms like omega-3 and omega-6 refer to the first double bond’s position from the end opposite the carboxylic acid.
    • Example: omega-6 has the double bond starting at the 6th carbon from the end, omega-3 at the 3rd carbon.

  • Exercise:

    • Draw a 14 carbon, 1 double bond omega-3 fatty acid:
    • Resulting structure must confirm:
      • Total carbons = 14
      • One double bond at third carbon
      • Ending with -COOH group as carboxylic acid.

  • Double Bonds in Fatty Acids

    • Natural double bonds result in bends in the fatty acid chain.
    • Example structures of saturated and unsaturated fatty acids display this phenomenon.
    • Cis vs Trans double bonds:
    • Cis double bond: Same side bending, creating a natural kink in the chain.
    • Trans double bond: Opposite sides, leading to straighter configurations, often found in man-made fats.

  • Health Considerations

    • Trans fats are less common due to health concerns and are man-made.
    • Natural cis forms with double bonds are more prevalent in whole food sources.

  • Next Steps

    • Upcoming content will discuss melting and boiling points of fatty acids.