A concise description of four important lipid types is given below. The focus is not on knowing molecular structures or chemical properties, but instead on understanding the biological functions.
- Fatty acids: Fatty acids are found in some foods and are made by the body. They store large amounts of energy. Fatty acids are very hydrophobic (repel water).
- Triglycerides: Triglycerides are three fatty acid molecules bonded together. Triglycerides make up over 90% of the stored fat in tissues.
- Phospholipids: Phospholipids are two fatty acid molecules bonded together. A phosphate group is also part of this molecule. While the fatty acid component of a phospholipid is hydrophobic, the phosphate group is hydrophilic (attracts water). Molecules that have both hydrophilic and hydrophobic parts are said to be amphipathic. Phospholipids are made by the liver and make up a large part of the cellular membrane.
- Cholesterol: Cholesterol is a lipid molecule that can be synthesized by our bodies and obtained from the diet. Cholesterol has many functions and will be discussed more in-depth throughout this presentation.
