GENERAL GEOLOGY

Detailed explanation-1: -In her 1967 article, Margulis suggested that “the first step in the origin of eukaryotes from prokaryotes was related to survival in the new oxygen-containing atmosphere: an aerobic prokaryotic microbe (i.e., the protomitochondrion) was ingested into the cytoplasm of a heterotrophic anaerobe.

Detailed explanation-2: -Fifty years ago, Lynn Margulis, inspiring in early twentieth-century ideas that put forward a symbiotic origin for some eukaryotic organelles, proposed a unified theory for the origin of the eukaryotic cell based on symbiosis as evolutionary mechanism.

Detailed explanation-3: -The theory postulates that the mitochondria evolved from aerobic bacteria (probably proteobacteria, related to the rickettsias), and that the chloroplast evolved from endosymbiotic cyanobacteria (autotrophic prokaryotes). The evidence for this theory is compelling as a whole, and it is now generally accepted.

Detailed explanation-4: -In her article, not only did Margulis champion an endosymbiotic origin of mitochondria and plastids from bacterial ancestors, but she also posited that the eukaryotic flagellum (undulipodium in her usage) and mitotic apparatus originated from an endosymbiotic, spirochete-like organism.

Detailed explanation-5: -In 1905, the Russian botanist Konstantin Mereschkowski first proposed symbiogenesis, or endosymbiotic theory. This theory states that organelles, which distinguish eukaryotes from prokaryotes, emerged though a mutually beneficial relationship between individual prokaryotes.