What is life ? We have to answer this question before looking for it. This isn't obvious. For the moment, we can only propose a partial definition (1,2,3,4,35)

It seems to be :

Properties of life:

• individualization: all organisms are individuals delimited by a membrane. They made an autonomous living entity.
• nutrition: they stay alive thanks to assimilation or production of the food they need to develop themselves or to maintain vital functions. This food becomes the substance of the organism that eat it.
• breathing/fermentation: organisms change the energy they find in food into energy that the cell can use, thanks to slow oxydation reactions.
• reproduction: all living beings can reproduce or divide themselves.
• evolution: all living organisms can evolve via mutations or natural selection.
• movement
• death

Life's functions:


• auto-conservation: to stay in life by nutrition, assimilation and by the energy reactions of breathing and fermentation.
• auto-reproduction: to spread life thanks to reproduction.
• auto-regulation: to lead itself, with coordination, synchronisation, regulation and control of reactions.

Living beings (1)


• Virus: capsule of protein containing a DNA molecule. It can't reproduce itself without infecting a cell.
• Bacteria: Cell with no nucleus (prokaryote), of two sorts: eubacteria and archaebacteria.
• Eukariote: cell with a nucleus including animals and plants.