When were viruses discovered?

Answer 1

Viruses were identified as non-bacterial toxic agents by many researchers beginning with Louis Pasteur in the 1870's, Charles Chamberland in 1884, and Dimitri Ivanovsky in 1892. Viruses were different because they could penetrate filters that stopped bacteria. Martinus Beijerinck defined the virus as an extremely small nucleotide particle rather than a fluid in 1898. It was not until 1935 that Wendell Stanley was able to crystallize viral particles, and they were imaged for the first time using an electron microscope in 1939.

Answer 2

There are only hypotheses from scientists about this since viruses do not leave a fossil record. They have been around since the first one celled organisms evolved. The three major theories are:

# Regressive Hypothesis = they may have been small cells that lived as parasites in larger cells and then evolved to eliminate the cell structures and genes that they no longer needed. (Also called the Degeneracy hypothesis.) # Cellular origin Hypothesis = they may have evolved from escaped bits of DNA or RNA that were leaked from the genes of larger organisms. (Also called Vagrancy hypothesis and Jumping Genes.) # Coevolution Hypothesis= they may have evolved from protein and nucleic acid molecules at the same time that cells first developed on Earth. If that is what happened, they would have lived in that state dependent on the cells for millions of years.

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Answer 3

1942