This type of molecule is not attracted to water (also referred to as hydrophobic), due to the non-polar covalent bonds that link hydrogen and carbon not being attracted to water's polar bonds. There are four main lipid groups. These include fats, waxes, phospholipids, and steroids.
Fats, as well as oils, are created when two kinds of molecules are combined. These include a type of alcohol known as glycerol and triglycerides (three fatty acids).
Phospholipids are soluble in oil and water. They include hydrocarbon tails that do not like water, and phosphate groups on the end that do like water. Human cell membranes are mostly made up of phospholipids that are classified in a double layer, with both layers' heads facing outward and tails facing inward.
Waxes are hard to break down and are insoluble in water. They are esters of alcohol. Wax creates a waterproof and protective layer on some bacteria, integuments of insects, plants, and animal fur.
Steroids are a cholesterol molecule's central core and it contains four fused rings. Cholesterol is an essential precursor for vitamin D and the sex hormones.