Why Are There Genes in Mitochondria

even granted the endosymbiotic origin of mitochondria, the persistence of mitochondrial genes and genomes requires explanation if most ancestral, bacterial genes have been successfully relocated to the cell nucleus, then why not all What is it about mitochondrial genes, or their gene products, that has prevented their successful removal to the nucleus  

The textbook The Molecular Biology of the Cell (Alberts et al. 1994) states the problem very clearly, and the following quotation has been retained, unchanged, from the first edition (1983). 

There seems to be no explicit proposal for the most widely held hypothesis for the persistence of mitochondria genomes, but the hypothesis is implicit in many discussions of mitochondrial structure and function. For example, and in contrast to the open question posed by Alberts et al., Cell and Molecular Biology Concepts and Experiments (Karp 2002) provides what is probably still the current consensus view. 

Carol A. Allen, Mark van der Giezen and John F. Allen 

according to this hydrophobicity hypothesis , proteins that are encoded and synthesised within organelles are characterised by shared, and extreme, hydrophobicity - all are intrinsic membrane proteins (Claros et al. 1995 Popot and de Vitry 1990 Von Heijne 1986). 

---