. Mitosis, a mechanism forthe distribution of chromosomes and chromosome equivalents developed with thehelp of tubulin. In
contrast to the flagelli of bacteria, eucaryotic flagelliand cilia are intracellular structures. The bundles of microtubuli are , justlike the rest of the cell's content, surrounded by a continuous membrane, theplasmalemma. Movement of flagelli occurs only, if energy in the form of ATP issupplied. The DNA of nearly all eucaryotes is always associated with basicproteins, the histones. This could mean that the interaction between histonesand DNA is not yet fully optimized at the evolutionary level of the protists. On 3. The existence of a nucleus is notthe same as the existence of a mitosis. During the division of the nucleus andthe cell, a seemingly confused tangle of threads appears. In numerousdinoflagellates, several accumulations of fibrillary looking structures occurduring the division of both the cell and the nucleus. The separation of thegenetic material occurs within the nuclear envelope. In contrast, the ribosomesfound in the cytosol of the eucaryotic host are all of the 80 S type. It isassumed that the rest of the information got lost during the course of evolutionas it was no longer required for the survival of the symbiont. In bacteria and in theinner mitochondrial membrane, the enzymes of the respiratory chain have thesame spatial arrangement. The essential enzymes of the bacterial and themitochondrial respiratory chain are homologous. The highest degree ofcorrespondence exists between the respiratory chain of mitochondria andrhodospirills. The DNA of
chloroplasts, nevertheless, contains introns whilethat of blue-green algae does not. The large and the smallribosomal
subunits of chloroplasts and bacteria complement each other. The DNA of chloroplastscontains just like the DNA of mitochondria relatively little geneticinformation. Many of the proteins identified and required in chloroplasts areencoded by the nucleus. A comparison between the ATP-synthetases ofmitochondria of varying origins and that of chloroplasts shows that the enzymesof both organelles share many similarities. Its corresponding genes are partlylocated in the nucleus, partly in the organelles themselves. The results givenas a scheme show that it is not always the same set of genes that is located inthe nucleus or the organelles, respectively. The cyanelles of the euglenophyte Cyanophoraparadoxa, for example, contain only 5 – 10 percent of the blue-greenalgae’s genome. The genes of the large and the small subunit of ribulose-1.5-bisphosphate carboxylase are located in the cyanelle genome. In green plants,the small subunit is encoded by the nucleus, the large subunit by the plastid. The large differences inthe pigmentation and the ultrastructure of the chloroplasts of red algae, brownalgae, diatoms, and green plants make a single incident as the initiation ofendosymbiosis unlikely. The ATP-synthetase ofbacteria and blue-green algae resembles that of organelles and consists of thesame amount of subunits. The symbiont is integrated into the host cell’splasma. The other examples show that the single steps leading to thetransformation of a procaryont into an organelle are separate and independentof each other. Cyanelles are thus good models for the in-detail analysis of theprocess of integration. What effects does theco-operation between the single compartments of the cell – the plastids,mitochondria, cytosol, and the nucleus - have ? Proteins like theATP-synthethase that consist of several subunits and the production of whichdepends on the interaction of different genomes received much attention. Itconsists of small and large subunits, that are encoded by the nucleus (thesmall subunits) and the chloroplasts (the large subunits) in eucaryots. Isoelectricfocussing, a variation of the electrophoretic separation, reveals anintraspecific variation of the small and the large subunit. The Latin names of the Nicotiana-speciesare given (epiheta). It can be seen clearly that the pattern of the largesubunit is the same in all Australian species and in some species of thewestern hemisphere. The latter is characteristic of many Nicotiana-species.The hybrids contain the gene products, in this case the small subunit ofRubisco, of both parental species. The large subunit is encoded by thechloroplast genome and as a consequence, only the genotype of the female parentcan be found in the hybrid. The large subunit is the same in all populationswhile the small one varies. This has already been done successfully in the caseof the genera Brassica, Triticum, and Solanum.