Origin of Life

gayakipe's version from 2018-02-27 07:21


From genetic recombination which is the combining of DNA from two sources contributes to diversity and occurs because of horizontal gene transfer. With horizontal gene transfer the movement of genes among individuals from different species which happens because of transformation, transduction, conjugation and gene transfer agents. Transformation is taking up an incorporating foreign DNA from the surrounding environment. Transduction is the movement of genes between bacteria by bacteriophages. Conjugation is the process where genetic material is transferred between prokaryotic cells. Gene transfer agents are virus like particles transfer random genomic sequences from one prokaryote to another. This genetic diversity gave way to endosymbiosis which is a symbiotic relationship in which one organism lives inside the body of a cell of another organism in which Archaea ingest bacteria. The endosymbiont theory, proposes that mitochondria and plastids were formerly small prokaryotes that began living within larger cells. Another possible way is that serial endosymbiosis happened which mitochondria evolved before plastids through a sequence of endosymbiotic events. The plastid lineage of protists evolved into red and green algae. Afterwards, on several occasions during eukaryotic evolution red and green algae underwent secondary endosymbiosis in which they were ingested by a heterotrophic eukaryote. The first multicellular forms were colonies collections of cells that are connected to one another but show little or no cellular differentiation. Afterwards, volvox was created which is the 1st multicellular organism. A second wave of diversification occurred when multicellularity evolved and gave rise to algae, plants, fungi and animals. Choanoflagellates were formed the closest living relatives of animals and charophytes the closest living relatives of plants.