Transcription of Mitochondrial DNA in HeLa Cells

In the last few years the investigation of the physicM properties of nfitochondrial DNA in eucaryotic cells has brought to light two remarkable facts. The first is that mitochondrial DNA has undergone an evolution, going from the simpler to the higher cellular organisms, in a direction opposite to that of the nuclear gonome. Whereas the latter has increased in size and complexity, mitoehondrial DNA has become smaller and simpler. Mitochondrial DNA molecules from lower euearyotic ells (protozoa, fungi) and plant cells have, in fact, been found to be considerably arger (from 3 to 12 times) than those of animal cells (Suyama and Miura, 1968; Wolstenholme and Gross, 1968; Wood and Luck, 1969; Borst, 1970);