A fatty acid is a carboxylic acid with a long, unbranched aliphatic chain. The aliphatic chain may be either saturated or unsaturated. Chains of even-numbered length predominate in nature. In biology, fatty acids are usually derived from triglycerides or phospholipids. Fatty acids are important components of cell membranes. When stored as triglycerides, fatty acids can be used as important sources of fuel for brain, heart, and skeletal muscle cells. Thermo Fisher Scientific supplies a broad range of fatty acids for research use. We also provide fatty acid and lipid derivatives such as sphingosines, ceramides, and phosphatidyl inositol phosphates.