Although it has been long been thought that the primary function of mitochondria is to generate ATP, there are several significant roles that the mitochondria play in cellular tissue and organ function. For example, the mitochondria are initiators of steroidogenesis (26) where cholesterol is first broken down to produce the precursor metabolites that are used to generate the steroids that mediate some of the key hormone responses that regulate our cellular, tissue and organ functions. Mitochondria also act as calcium stores where careful regulation of calcium ensures that cells function efficiently (27). Indeed, too much uptake of calcium within a mitochondrion can lead to depleted cell function or even cell death. Consequently, mitochondrial homeostasis of calcium is an important regulator of cell function. Finally, it is becoming increasingly evident that the metabolites that are generated from the mitochondria can be important regulators of DNA methylation. Factors associated with the citric acid cycle, such as modulators of α-ketoglutarate, can regulate families of proteins, such as the TET proteins, which modulate the transition from 5’-methylcytosine to 5’-hydroxymethylcytosine, namely the transition of DNA from a methylated to a demethylated state (28-30). This area of investigation is becoming increasingly important in our understanding of global DNA methylation events during early development.