kramerj@ucs.orst.edu (Jack Kramer - OSU Gene Res) (07/20/88)
Tried to followup on this before in response to a similar question but it bounced. I assume from your question you are asking about eukaryotic cells. Lynn Margolis has made this subject her life work and she is an excellent author. She has published several books. They give a very good popular literature level introduction to the subject. She is very strongly biased to her own theories but does give references so one can branch out form there. Her theories have become pretty much the paradigm in this area but there is still a good deal of controversy especially when organelles other than mitochondria and chloroplasts are considered. I prefer an alternative hypothesis mentioned only a few time in the literature but which makes much more sense to me than the Serial Symbiosis hypothesis. It seems much more probably to me that the first eukariotic cells evolved from obligate symbiotic agregates of prokariotic cells. The pro-mitochondria and pro-chloroplasts probably formed the first such associations which are most justifiable on physical and chemical grounds. The two or so billion years during which the prokariotes were the only form of cellular life is provides the long times necessary. the close coupling of the capture and use of the sun's energy in photosynthesis and respiration would provide strong selective pressure to maintain and optimize this relationship. Cycles like this can easily create spinoff eddies of energy which could then be tapped to further enhance the association. Eventual joining of the group by the protonucleus then gave the addvantage of the eukariotic genomeic apparatus. the association became so advantageous that an enveloping envolope evolved to protect and isolate the minimum group of organelles. A corallary to this is the possibility of several origins of the eukariotic lineages. Anyone tryuing to make sense out of the phylogeny of unicellular eukariotes such as the algae, fungi and protozoa should welcome this suggestion. A couple of other anthologies are: Origins and Evolution of Eukaryotic Intracellular Organelles Edited by Jerome Fredrick The Origin of Eukaryotic Cells Edited by B D Dyer and R Obar The origin of the prokaryotic and protoeukaryotic cells which evolved into the (controversially) more advanced and complex eukaryotic cells is voluminously covered under the subject of prebiotic evolution. Jack Kramer kramerj@ucs.orst.edu cmathews.kramer@bionet-20.arpa