Plasmids are additional small DNA molecules typical for bacteria. During the last years did they become indispensable tools of genetic engineering. It seems as if the hybrid proteins produced in the CMS varieties would be deposited in the inner mitochondrial membrane and would impair its function. This guarantees that one type is transported into one organelle, another into a second organelle while a third type may remain in the cytosol. Enzymes of the same activity and specificity but of different structures and reaction kinetics are called isoenzymes .
Mitochondria develop by division, too.
While in animal cells only the interactions of the nuclear and the mitochondrial genomes have to be regarded, are we confronted with an interaction between nuclear, chloroplast and mitochondrial genomes in green plants. Especially the inner mitochondrial membrane can only be passed selectively even by low molecular weight metabolites. The carriers within this membrane cause the selectivity and control the transport rate. But the most important feature of mitochondria is the respiratory or oxydative phosphorylation . It consists of two functional parts, the electron transport chain and ATP synthesis , the original phosphorylation.