Lipids

Lipids

Lipids are used for insulation, protection, and the long term storage of energy in animals. They also make some hormones and are the structure of the cell membrane (phospholipids). Neutral fats are called triglycerides, of which there are 2 types:

1. Saturated Fats have no double bonds in the carbon chains. They are unhealthy, mostly come from animals, and become solid at room temperature. The carbons in saturated fats are filled with hydrogens.

2. Unsaturated fats have either one (monounsaturated) or more (polyunsaturated) double bonds. They are healthier, mostly come from plants, and are liquid at room temperature.

These triglycerides are composed of 3 fatty acids bonded to one glycerol through dehydration synthesis. The fatty acids contain a long chain of 16-18 carbons and have an acid end. The glycerol in a triglyceride is a small 3 carbon chain with 3 alcohol groups.

Phospholipids

Phospholipids are used to make up the two-yearlayered cell membrane of all cells. The third fatty acid group of a triglyceride is replaced with an inorganic phosphate group. This end is hydrophilic (water soluble), while the polar tail is hydrophobic (not water soluble).

Steroids

Steroids are made up of four carbon ring molecules fused together. They are used as either a sex hormone, such as testosterone, or vitamin D or cholesterol.