Naked Science Forum

Life Sciences => Cells, Microbes & Viruses => Topic started by: Martin on 15/10/2011 14:30:02

Title: What criteria define life?
Post by: Martin on 15/10/2011 14:30:02

Martin asked the Naked Scientists:
   
What are the seven criteria for defining life?

What do you think?

Title: What criteria define life?
Post by: CliffordK on 16/10/2011 08:29:54

There are seven criteria?  Sounds like a quiz question.

Ok, I think I'd start with:

1) Self Reproduction.
2) Some kind of energy conversion
3) Some kind of chemical or matter conversion
4) Some kind of containment, or boundaries.

Hmmm,
So, I've gotten 4.
Do I really need 3 more criteria?

One can certainly describe terrestrial prokaryotes and eukaryotes.  But, in many senses, one needs a definition that would extend to Life in general.

Viruses and Phages are always troubling as they may share some characteristics or other living organisms, but they are unable to perform cellular functions without a host cell which performs most of the tasks of life.

One also has problems like if one asks whether FIRE is alive?

Title: What criteria define life?
Post by: Airthumbs on 16/10/2011 09:48:04

The exact list you are looking for is here;  http://en.wikipedia.org/wiki/Life

Title: What criteria define life?
Post by: cheryl j on 01/11/2011 16:32:25

In some textbooks the criteria for life are:
self reproduction
metabolism
organization
response to stumuli

Title: What criteria define life?
Post by: Mazurka on 02/11/2011 10:17:53

Quote from: cheryl j on 01/11/2011 16:32:25

In some textbooks the criteria for life are:
self reproduction
metabolism
organization
response to stumuli

Oh no,  that suggests that some of my colleagues - who lack both organisation and seldom respond to stimuli - are not alive!