Peroxisomes are small organelles with a single-membrane involved in many metabolic interactions such as oxidation of fatty acids (Cooper, 2000). They are synthesized on free ribosomes and imported into peroxisomes as completed polypeptide chains. Peroxisomes replicate by fission and do not contain their own DNA. The main task of the peroxisome is to oxidize fatty acid chains into acetyl co-enzyme A, a major source of metabolic energy. In this process, hydrogen peroxide is created as a bi-product. However, the peroxisome contains a substantial amount of the enzyme, catalase, which is able to decompose hydrogen peroxide into water and oxygen. In addition, the hydrogen peroxide can be used to oxidize other substances such as phenols, formic acid, and formaldehyde, thus ridding the cell of the toxin. Peroxisomes have slightly altered functions in different areas of the body. In liver cells for example, they are involved in the synthesis of bile acids, while in animal cells, they aid in the synthesis of dolichol and cholesterol. Another extremely important function of the peroxisome is the biosynthesis of a phospholipid called plasmalogen. The ester bond to glycerol is replaced with an ether bond. This lipid is essential for membrane components in brain, heart, and lung tissue (Cooper, 2000).
Though the peroxisome is a small organelle, defects in it are extremely serious and can cause a host of physiological problems. Zellweger's Syndrome is an autosomal recessive disorder part of a family of diseases called peroxisome biogenesis disorders (NINDS, 2012). Biogenesis disorders are caused by mutations in PEX (peroxisomal biogenesis factor) genes 1, 2, 3, 5, 6, 10, 12, 13, 14, 16, 19, and/or 26. These genes encode peroxins, which are proteins essential in the formation and further development of peroxisomes. Defects in PEX genes lead to tissues and cells accumulating long-chain and branched-chain fatty acids that are normally degraded within the peroxisome, as previously described.