Have the maximum number of hydrogen atoms possible.
Have no double bonds in their carbon chain.
Are solid at room temperature.
Unsaturated Lipids
Have one or more double bonds.
Oils are examples.
They are liquids at room temperature.
When hydrogenated (by adding more hydrogen), they become solid and saturated.
Fatty Acid Bonding Structure
Saturated fatty acids: single bonds.
Unsaturated fatty acids: contain at least one double bond.
Trans Fats
Trans unsaturated fatty acid (trans fats):
The chemical process used to saturate unsaturated fatty acids can lead to trans fats.
These have a double bond that results in a linear chain.
Do not form naturally.
Do not function well in biological systems.
Are a health hazard.
trans double bond vs cis double bond
Trans Fat: Margarine
Margarine is a trans fat that was developed during World War II.
Due to a milk and butter shortage, scientists took corn oil and hydrogenated it.
The double bonds became single bonds, and a solid was formed.
Health Hazards of Trans Fats
Trans fats tend to stay in the bloodstream much longer than saturated or unsaturated fats.
Trans fats are much more prone to arterial deposition and plaque formation.
Scientists have studied whether trans fats could play a role in the following diseases and disorders:
Cancer
Alzheimer's disease
Diabetes
Obesity
Liver dysfunction
Infertility
Their role remains unclear.
Amphiphilic Lipids: Soaps and Detergents
The hydrophobic end of a soap or detergent is repelled by water but attracted to other non-polar molecules, like grease and oil.
The hydrophilic end of the soap or detergent forms hydrogen bonds with water.
Soaps and Detergents
The soap or detergent bonds with many stains (oil, grease, etc.), pulls them from the surface being cleaned and into micelles in the surrounding water.
The water and micelles then go down the drain, along with the oil or grease, leaving the surface clean.
Waxes
Waxes are effective hydrophobic coatings formed by many organisms (insects, plants, humans) to ward off water.
They often consist of 2 long fatty acids connected by oxygen-containing groups.
Steroids
Lipids with backbones that form rings.
Examples:
Cholesterol is an important component of cell membranes.
Male and female sex hormones, testosterone and estrogen, are also steroids.