Fatty Acids: Saturated vs. Unsaturated

Lipids

• Lipids are a chemically diverse group of organic compounds, characterized by their insolubility in water.
• Lipids are highly soluble in non-polar solvents, such as chloroform and ether.
• Lipids are essential to the overall energy economy of the cell.

Fatty Acids

• Fatty acids are long hydrocarbon chains with varying lengths and degrees of unsaturation, terminating with carboxylic acid groups.
• Carbon atoms in fatty acids are numbered starting from the carboxyl terminus.
• Systematic names of fatty acids are derived from the name of their parent hydrocarbon by substituting "oic" for the final "e".
• Examples of fatty acids: Octadecadienoic acid, Stearic acid (saturated), and Linoleic acid (unsaturated).

Saturated and Unsaturated Fatty Acids

• Saturated fatty acids have no double bonds and carry the maximum possible number of hydrogen atoms.
• Unsaturated fatty acids lack hydrogen atoms and have at least one double bond.
• Examples of unsaturated fatty acids: Linoleic acid (C18:2 ω6) and α-Linolenic acid (C18:3 ω3).

Cis and Trans-Fatty Acids

• Cis fatty acids have hydrogen atoms on the same side of the double bonds.
• Trans fatty acids have hydrogen atoms on opposite sides of the double bond.

Essential and Non-Essential Fatty Acids

• Non-essential fatty acids are produced by the body.
• Essential fatty acids are derived from the diet, are not produced by the body, and are necessary for vital functions.

Triglycerides

• Triglycerides are formed from a molecule of glycerol and three fatty acids.
• Triglycerides are major components of very low density lipoprotein (VLDL) and chylomicrons.
• Triglycerides are important in metabolism as energy sources and transporters of dietary fat.

Phospholipids

• Phospholipids contain one or more fatty acids attached to a phosphate and an alcohol.
• Phospholipids may be attached to glycerol, a 3-carbon alcohol, or sphingosine.
• Examples of phospholipids: Cardiolipin (found in the heart) and Sphingomyelin (found in the brain).

Glycolipids

• Glycolipids are sugar-containing lipids derived from sphingosine.
• Glycolipids differ from sphingomyelin in the identity of the unit linked to the primary hydroxyl group of the sphingosine backbone.
• Example of glycolipid: Cerebroside (found in neural tissue).

Sterol Lipids

• Cholesterol is built from 4 linked hydrocarbon rings.
• A hydrocarbon tail is linked to the steroid at one end, and a hydroxyl group is attached at the other end.
• In membranes, the orientation of the molecule is parallel to the fatty acids chains of the Phospholipids, and the hydroxyl group interacts with the nearby Phospholipid head groups.
• Example of sterol lipid: Bile Salt, which originates from cholesterol and has 4 linked hydrocarbon rings plus Taurine or Glycine or Both.

Lipid Profile

• High Density Lipoprotein Cholesterol (HDL-C): >1.2 mmol/l
• Low Density Lipoprotein Cholesterol (LDL-C): 2.4 mmol/l
• Triglyceride