Chapter 12 Biogenesis of energy-transducing systems

This chapter discusses the biogenesis of energy-transducing systems. The fundamental function of biological membranes is to separate components and to maintain different compositions of solutes in the separate spaces. Therefore, essentially every biological membrane functions in energy transduction. The maintenance of the different compositions in the two sides of the membrane is based on its functional asymmetry. The degree of asymmetry varies from uneven distribution of lipids in the bilayer up to absolute polarity of large protein complexes in the membrane. This asymmetry arises from the vectorial assembly of the individual protein complexes into the membranes in vivo where a high degree of specificity is maintained. The chapter discusses only the biogenesis of energy-transducing organelles of the eukaryotic cell. Among the unique features of the eukaryotic cell—the separate nucleus, the developed secretory pathway and the inclusion of semiautonomous organelles were very decisive for the development of its nature. Though most of the genetic information is stored in the nucleus; chloroplasts and mitochondria retain control over synthesis of several of their proteins through their own unique DNA and RNA molecules and protein-synthesizing machinery. Some features of the protein-synthesizing machinery in chloroplasts and mitochondria closely resemble those of prokaryotes. Most of the oligomeric membrane protein complexes of mitochondria and chloroplasts are synthesized—partly by cytoplasmic and partly by organelle ribosomes.