Lipids and Fatty Acids Overview

Lipids

• Lipids are classified into simple and complex, based on whether they contain saponifiable fats or not.

• Simple lipids contain fatty acids. Complex lipids lack fatty acids.

• Under "Simple" are subclasses:

  • Acilglycerols
  • Waxes

• Under "Complex" are subclasses:

  • Phospholipids (phosphoglycerides, sphingolipids, and glycosphingolipids)
  • Isoprenoids (terpenes and steroids)
  • Prostaglandins

Fatty Acids

• A saturated fatty acid contains no double bonds in the hydrocarbon chain.

• An unsaturated fatty acid contains one or more double bonds in the hydrocarbon chain.

  • Cis fatty acids contain carbon-carbon double bonds where H atoms are on the same side of the double bond.
  • Trans fatty acids contain carbon-carbon double bonds where H atoms are on opposite sides of the double bond.

• Examples of fatty acids:

  • Stearic acid
  • Oleic acid
  • Linoleic acid

• The chemical formula for saturated fatty acids shows a long chain with -CH2- groups between the terminal methyl (-CH3) end and the terminal carboxyl group (-COOH).

• The chemical structure shows angles of 110° between carbon atoms.

Esterification and Saponification

• Esterification is the reaction between an acid and an alcohol, producing an ester and water.
• Saponification is the reverse reaction, breaking down an ester into an acid and an alcohol using a base (e.g., sodium hydroxide).

Triglycerides

• Triglycerides are formed when glycerol reacts with three fatty acids via esterification.

Phospholipids

• Phospholipids are complex lipids containing a phosphate group.
• Phospholipids in a cell membrane have hydrophobic tails and hydrophilic heads.

Steroids

• Steroids like cholesterol have a fused ring structure .

Examples from the diagrams:

• Colesterol and Estradiol are steroids with complex ring structures.

• Acid Palmític, Acid Esteàric, Acid Oleic and Acid Linoleic are fatty acids found in diagram .

• Phosphatidylethanolamine, Phosphatidylserine, Phosphatidylcholine, and Sphingomyelin are examples of phospholipids.

Fats vs Oils

• Fats are typically solid at room temperature and are usually saturated fatty acids.
• Oils are typically liquid at room temperature and are usually unsaturated fatty acids.

Soap Production

• A process of using a base (sodium hydroxide or potassium hydroxide) to convert lipids (e.g., olive oil) into soap are shown in the diagrams.