Over the past twenty years, a lot of the new evidence on the role of mitochondria in the cell has been shocking and unexpected. Almost no one thought that mitochondria could control the regulation of genes in the nucleus—both on a daily basis and during cell growth and differentiation. Their interaction with and regulation of other organelles, such as the endoplasmic reticulum and lysosomes, were also surprising. They were usually thought of as relatively insignificant, and very small, ATP factories. They were sometimes described as “little batteries.”
