EVOLUTION OF EUKARYOTIC CELLS

We sometimes, during the weirdest and rarest scenario wonder who is our pre, pre, pre, pre...... Ancestor other than common term monkeys ?? How did we evolve, How did life evolve ?? How cells evolved ?? The answer leads the way back to pre-historic tales. Once upon a time million years ago...... Back to our point. We have two kinds of cell forms existing on Earth Prokaryotes and Eukaryotes but, Prokaryotes itself evolved from Eukaryotes. Fossil records indicate that eukaryotes evolved from prokaryotes somewhere between 1.5 to 2 billion years ago. Two proposed pathways became successfully included as part of a now much larger cell with additional structures capable of additional functions as follows: * Endosymbiosis * Membrane infoldings ENDOSYMBIOSIS: Research conducted by Lynn Margulis at the university of Massachusetts supports the hypothesis that two separate mutually beneficial invasions of a Prokaryote cell produced the modern-day Mitochondria and chloroplast as eukaryotic cell's organelles. In this model, ancestral Mitochondria were small heterotrophs capable of using oxygen to perform cellular respiration and thereby create useful energy. They became a part of a large cell either by direct division as an indigestible food source. Later a second invasion as in brought ancestral chloroplasts, which are thought to be small, Photosynthetic Cyanobacteria. Modern-day supporting evidence for endosymbiosis shows that both the mitochondria and chloroplasts have their own genes, circular DNA and RNA, and reproduce by binary fission independent of the host's cell cycle. They therefore appear to be more similar to Prokaryotes than Eukaryotes. MEMBRANE INFOLDING: The invasions of the host prokaryotes cell probably were successful because the host cell membrane infolded to surround both invading prokaryotes cells and thereby help transport them into cell. The membrane did not dissolve but remained intact and thereby created a second membrane around the protomitochondria and chloroplast. It is also known that in modern-day eukaryotes the inner membrane of both the mitochondria and chloroplast contain structures more similar to prokaryotes than eukaryotes, whereas the outer membrane retains eukaryote characteristics !! It is also suggested that continued membrane folding created the endomembrane system. It can be said that possibly the first eukaryotic cell type was miraculously born from prokaryotic, symbiotic, multicell interactions. This proves that all organisms has/had a base millions of years ago which faced its own evolution and went through various changes to exist today. Thus, to understand an modern-day organism studying its evolution plays a vital role.