DNA vs Life
Date: November 2008
If DNA is non-living, how come human beings live?
By using the code as a template, living proteins can produce more proteins,
or can even replicate the DNA itself. The ability to copy itself is what makes
DNA the molecule of life - even when it is also a non-living chemical like any
other. Some would say that DNA is the boundary between living and non-living -
and may even represent the definition of what is living.
For many years scientists puzzled over viruses - which are just lumps of DNA.
You can extract many viruses from plants and store them in a jar, looking like
fine sand, or even as course crystals in some cases. They are inert - they do
nothing - not breathe, not respire, not reproduce - they stay in the jar for
years doing nothing. But let them out of the jar and they cause disease in
plants again - the same disease you saw in the plant you got the virus from
in the first place. How? -- The inert, non-living DNA in the virus is able
to take over and reprogram the plant cells to copy the virus DNA rather than
its own, thus the plant makes new virus, rather than producing new plant cells.
So DNA represents life at the molecular scale. A single strand of DNA cannot
be alive on its own - but a cell cannot be alive without the DNA
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Update: June 2012