Evolution of cell and chromosome structure in eukaryote.
The analysis of the data so far available indicates that eukaryotic chromosome with splicing characteristics appeared quite early in evolution possibly parallel and not sequential to the prokaryotic system. The endosymbiotic origin of the eukaryotic cell involved a primitive undifferentiated unicellular eukaryote and a photosynthetic or non-photosynthetic microbe. Certain regulatory genes of extra-cellular organelles were transferred later through molecular hybridization to the nucleus. The evolution of multicellularity and sexual reproduction led to the origin of innumerable eukaryotic forms in the late precambrian period. This new concept of the author can account for the evolution of complex eukaryotic chromosome and harmonious functioning of extra-cellular organelles with the nucleus. The concept also explains the sudden spurt of innumerable eukaryotic fossils at the early palaeozoic era.
Sharma
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AK
D000818:Animals; D005075:Biological Evolution; D002477:Cells / Q000166:cytology*; D002875:Chromosomes / Q000648:ultrastructure*; D005057:Eukaryotic Cells / Q000166:cytology*; D005809:Genes, Regulator; D008957:Models, Genetic; D011387:Prokaryotic Cells / Q000166:cytology