In a single cell, there are a large number of organelles called mitochondria. These organelles are spherical with a double membrane, the outer mitochondrial membrane and the inner mitochondrial membrane (Chial). The majority of energy and energy in the body's cells, more than 90% of what is needed to preserve life and promote growth, comes from these organelles in the form of the molecule adenosine triphosphate (Kurt 11 ; " What "). This energy production process is called oxidative phosphorylation because it occurs in the presence of oxygen (Sirrs). If there is a defect in this assembly of energy within the mitochondria, we speak of mitochondrial disease. Usually, the organs affected by these diseases are those that require greater amounts of energy, such as the heart, brain, muscles, and liver (Kurt 11). When this mitochondrial disease process occurs throughout the body, it can affect entire body systems and lead to possible death (“What”). However, the production of adenosine triphosphate is only one function of mitochondria. Most of the roles of mitochondria depend on the location of the cell in which they occupy and the functions of the cell. As a human develops from fetus to adult, the functions of these mitochondria also change and develop. Most of these tasks of mitochondria are primarily engaged in anabolism, "molecular building blocks" and catabolism of fats, proteins, carbohydrates, etc. For example, cells cannot even form RNA and DNA without the help of mitochondria, because they require purines and pyrimidines formed in the organelle. In addition, mitochondria retain the “limiting enzymes” necessary for pyrimidine biosynthesis and heme synthesis necessary for hemoglobin production. Another distinction...... middle of document ......G, Yolanda Lillquist, MD, FRCPC. “Clinical manifestations of mitochondrial disease: an overview”. British Columbia Medical Journal 53.4 (2011): 183-87. British Columbia Medical Journal. Internet. April 18, 2014. Sirrs, Sandra, MD, FRCPC, Margaret O'Riley, RN, MA, Lorne Clark, MDCM, FRCPC,FCCMG, and Andre Mattman, MD, FRCPC. “Primer on mitochondrial diseases: biochemistry, genetics and epidemiology.” British Columbia Medical Journal 53.4 (2011): 172-76. British Columbia Medical Journal. Internet. April 18, 2014. “What is mitochondrial disease?” What is mitochondrial disease. United Mitochondrial Disease Foundation, nd Web. April 19. 2014. .