DESCENT WITH MODIFICATION 3 Yes it was a whole new ballgame once free oxygen became available. New utilization parameters for energy now were possible when new chemical combinations occurred. A chemical called Ubiquitin arose as well as some which were called cytochromes and they found an association with one another which was energetically useful to each of them and which when they associated with some of the membranes and DNA/Protein/RNA combinations formed some bacteria like cells which utilized Oxygen as an electron acceptor. These cells acquired a cell wall by fusion with other anaerobic bacteria so that they became fully aerobic bacteria. As time passed the aerobic and anaerobic bacteria both the heterotrophic and autotrophic ones (the ones that got food from outside of themselves and the ones who made their own food) diversified until every niche in the thermally moderating environment had been occupied. For millennia these organisms lived and proliferated in their various niches as the environment in many areas moderated even more. However, as some environments moderated some became more extreme with high salt, high acid and high temperatures as well as high pressure. A new form of single celled organism slowly developed which was able to occupy these new environments. They were similar to bacteria in being without a nucleus or any membrane bound intracellular structures though their cell wall material and their translational apparati were slightly different. Ultimately, they moved into all of the extreme environments previously mentioned and began to produce large amounts of methane among other by products. All of these by products contributed to the environmental gas mixtures which we see today with 78% Nitrogen and 21% Oxygen with Argon and Carbon Dioxide and a few other gasses making up the rest (Though the amount of Carbon Dioxide is increasing due to carbon pollution from Human endeavors). This new form of prokaryote became known as Archaea. 1977, Woese and Fox published a paper containing just one table illustrating the relationships between the ribosomal RNA fragment catalogs of 13 species. The data revealed three distinct groups, which Woese and Fox described as “urkingdoms”: eubacteria, archaebacteria, and urkaryotes—their name for the presumed ancestor of the eukaryotes. Though some scientists balked at the idea of three urkingdoms replacing the conventional two, the three domains of life—Archaea, Bacteria, and Eukarya—eventually became widely accepted. With the more recent availability of vast amounts of genomic data, some now challenge the three-domain tree of life, and instead support a tree where Bacteria and Archaea are the sole domains, with Eukaryotes branching from the Archaea. But Woese’s three domains have not lost their stronghold in biology dogma just yet. Fox wonders if the Achaea would have been missed if a different technique had been employed. Fingerprinting gave “a much more black-and-white outcome than you would have if you were actually using modern sequencing,” he says. With the percent identity comparisons that scientists use today, “Achaea would probably just be considered an odd niche of bacteria.” As more time passed one particular Archaean group lost some of its integrity of cell wall and fused with some more of the phospholipid membranes which were found as remnants of other Achaea which had died and these surrounded the Archaean genetic material with a double layer and some of these Archaea were able to reproduce themselves through an unusual sort of binary process wherein some proteins had attached themselves to the chromosomes and copies of these separated after duplicating one another and the protein spindles which anchored themselves in other protein which we later called centrioles contracted and pulled the chromosomes into opposite sides of the cell which stretched and underwent a sort of modified fission process producing two duplicated cells which had chromosomes surrounded by a double membrane and which had grown considerably larger in the process of accumulating the spindle apparatus and the double layered nuclear membrane. These cells were primitive ancestral Eukaryotic cells, urkaryotes, from which the first diplomonads (the most primitive extant group of protozoans and Chlamydomonas (the most primitive of the Volvocine line of green algae), arose. Once the foundations were laid for the evolution of animal and plant Eukaryotic cells, the domain Eukarya was off and running and descent with modification leading to humanity was going strong.
Posted on: Sun, 23 Mar 2014 01:29:14 +0000
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