On 29/05/2006, at 3:26 AM, Ronn!Blankenship wrote:
So:
(1) virus ( ) alive ( ) not alive.
(2) BSE prion ( ) alive ( ) not alive.
(Choose one and only one answer to each question.)
You're making a classic error, of forcing things into pigeonholes.
There are some things that are alive, some not, and some that are
"life-like", that miss on one of the factors that define things as
living, but still behave like living things. I could say that yes,
viruses are "alive", and "prions" are not. But it's actually
meaningless at this level. Both evolve.
Living Elephants Badgers Squid Seqouias
Seaweed Tapeworms Sponges
Slime Moulds Nematodes
Amoebae Flagellates Diatoms
Salmonella
Archaebacteria
TMV, phages
HIV, ebola
"naked RNA" virions
prions
enzymes
proteins
organic chemistry
Non-Living chemistry
Where do you draw a line? Between the archaebacteria and macrophages?
Some viruses are as big or bigger than some bacteria. They do
everything except metabolise - they piggy back on a host's
metabolism. Yet when they have that environment, they reproduce and
adapt and evolve.
Unlike evolution, defining life is *not* a settled question. The list
I gave of properties of life is just a variant of one of the systems
- there are others. If even biologists can't agree on this, I see
little hope in there ever being a clear-cut definition of life. Maybe
there shouldn't be one.
Charlie
_______________________________________________
http://www.mccmedia.com/mailman/listinfo/brin-l
