Like living things, viruses evolve through time and thus can adapt to their environment. DNA controls the evolution of the cell and the organism. Having genetic material is an important step towards being classified as alive.
Viruses and the evolution of life pdf code#
It has been suggested that replacement of cellular proteins by viral ones also occurred in early evolution of the DNA replication apparatus and/or that some DNA replication proteins originated directly in the virosphere and were later on transferred to cellular organisms. Viruses do have DNA or RNA, and DNA is the code for life. Viral proteins have replaced the ancestral bacterial RNA/DNA polymerases and primase during mitochondrial evolution. The antiquity of viruses can explain why most viral proteins have no cellular homologues or only distantly related ones. Theoretical considerations suggest that RNA viruses may have originated in the nucleoprotein world by escape or reduction from RNA-cells, whereas DNA viruses (at least some of them) might have evolved directly from RNA viruses. the virus first, the escape and the reduction hypotheses are revisited in this new framework. The three current hypotheses for virus origin, e.g. Viruses infecting cells from the three domains of life, Archaea, Bacteria and Eukarya, share homologous features, suggesting that viruses originated very early in the evolution of life.
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