Viruses: Complex Molecules or Simple Life Forms?
Viruses have been defined as "entities whose genomes are elements of
nucleic acid that replicate inside living cells using the cellular synthetic
machinery, and cause the synthesis of specialised elements that can transfer the
genome to other cells." They are stationaryand are unable to grow. Because of
all these factors, it is debatable whether viruses are the most complex of
molecules or the simplest life forms. While the definition of living organisms
must be adapted, the majority of evidence leads to the classification of viruses
as living organisms.
Viruses are composed of a nucleic acid core, a protein capsid, and
occasionally a membraneous envelope. The nucleic acid core is composed of
either DNA or in the case of retroviruses, RNA, but never both. In retroviruses,
the RNA gets transcribed to DNA bye the enzyme reverse transcriptase. The
protein capsid is a protein layer that wraps around the virus.......
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