The Mitochondrion

Abstract

Mitochondria have long been one of the most studied subcellular organelles, Why is this? Firstly, their size (up to 5 µm long) and characteristic morphology meant that they were readily identified by Microscopists. Secondly, they house numerous important reactions of oxidative metabolism, in particular those leading to the synthesis of ATP. Thirdly, they contain all the genetic machinery required to express several mitochondrial components, and thus have a degree of autonomy from the nucleus (a characteristic shared with chloroplasts, section 9.5). In this text, we cannot consider in detail the morphology of mitochondria, nor the numerous reactions of intermediary metabolism that occur there; these aspects are well covered in standard biochemistry textbooks. Instead, we shall focus on three important areas of research concerning mitochondrial structure and function: the generation of ATP by oxidative phosphorylation; the genetic machinery of these organelles; and their biogenesis and evolution. First, however, we need to set the scene by outlining the contribution that the mitochondrion makes to cellular function.