31 Days – The Boundary of Life

Many of life’s most interesting questions are about the boundaries between things.

  • Where does a white lie become just a lie?
  • Where does art become non-art?
  • Where does innocence become ignorance?
  • Where does charity become enablement?

Perhaps the most interesting boundary question of all is, where does life become nonlife? Here’s a list of …um… things. Where would you draw that boundary?

E. Coli

Bacteria (E. Coli)

Bacteria  – Each is a single, prokaryotic cell. They metabolize, grow and reproduce. Alive, right?

Archaea (Halobacteria)

Archaea (Halobacteria)

Archaea — Even simpler than bacteria, archaea have no membrane-bound organelles. They are famous for their variety, with some able to live in environments previously thought uninhabitable, or obtain energy from inorganic sources such as sulfur or ammonia.

Rotavirus

Rotavirus

Viruses — A virus has genetic material (either DNA or RNA), a protein coat, and sometimes an envelope that helps the virus identify and enter the cells it infects. Viruses reproduce (big-time) but they do not have their own metabolism, instead hijacking the metabolism of their hosts.

Brain Tissue with Mad Cow Disease

Brain Tissue with Mad Cow Disease

Prions  — A prion is nothing more than a badly folded protein. Unlike bacteria and viruses, it has no DNA or RNA. However, it does reproduce, vampire-fashion, by converting well-folded proteins to misfolded ones, which go on to convert others. Prion structures even “grow” by forming fibrils that extend at each end. Prions are in the cause of nasty-sounding illnesses including mad cow disease, chronic wasting disease and scrapie.

Meteorite Bearing Amino Acids

Meteorite Bearing Amino Acids

Organic molecules from outer space — Amino acids, well-known as the building blocks of life as we know it, have been found on meteors. Cool, right?

Surely by the end of that list we have arrived at nonlife. But when did we make the transition?

Before 1828, scientists believed that the chemistry of living things differed from that of nonliving things. That notion has been thoroughly refuted and now “organic chemistry” simply means chemistry that involves carbon.

That ball has continued to roll, and now the distinction between life itself and nonlife is far from clear.

It makes you wonder…

2 responses to “31 Days – The Boundary of Life

  1. Doesn’t it go back to absolutes and relativism? The reason it is unclear is because it is based upon the opinion of the observers which varies drastically. So what it comes down to is whose opinion a person wants to embrace. Why? Because the definition of life has become abstract, unlike applied math which is concrete. In order for scientists to properly define the line that divides life from non-life, they must first discover the concrete meaning of life. How? It starts with linguistics and ends with proving what they find whether true, false or something else.

  2. Pingback: Archaea – articles4friends

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