Cells and the criteria of life

[physarrista]

Do all cells and microorganisms fulfill the criteria of life?

Homeostasis
Organisation
Metabolism
Growth
Adaption
Response to Stimuli
Reproduction

I'm asking, because I know that there are animal species which don't fulfill all those criteria (I know a mule can't reproduce) and I was wondering if there are bacteria or cell lines out there which for example don't grow or something. It doesn't seem possible to me, but with biology you never know..

 

[jim mcnamara]

Depends on what you consider a microorganism - viruses and prions do not meet most of those criteria, but the general of view of these beasties is that they are not really living.

If you include things that metabolize when they are in an active phase (not parked inside a spore for example), then I think the answer is yes. This would discard viruses, for example.

 

[Spirochete]

It's true an entire mule can't reproduce, but many of its cells surely can.

 

[physarrista]

Yeah.
Some googling revealed, there seems to be some kind of debate out there about the criteria anyways.
I remember learning "movement" as an attribute of life in high school biology class. This seems to have been taken off the list, since.

 

[Spirochete]

Search around this site, Jim or some other frequent poster has already written prolifically about grey areas in biology and how to think about them.

 

[Cincinnatus]

It wouldn't be difficult to write a computer program that simulates agents having all these properties. Indeed lots of research along these lines is carried out in the field usually called "artificial life".

" Are those agents really "alive"? " Is probably more a philosophy of language question than anything else.