What exactly constitutes life?

[someguy]

Not knowing much about biology, I was wondering what makes something considerd to be alive?
At what level is life considered to be there? Is a virus a life form? Bacteria?
How much do we know about the makeup of life? DNA?
Thanks,
Some Guy

[ronthepon]

Life is separated from the lack of it by activity of DNA. If stuff is being produced, used and made an a cell, it is alive.

Viruses are considered semi-life forms, they are at the border of living and dead.

Bacteria are full scale life forms.

We know so much about the makeup of life that it will leave your head spinning. DNA is a very very known thing, we know a huge lot of what it is, does, makes, etc.

[hallenrm]

A fairly good discussion of this question, can be found on wikipedia.

Life

Then, there is this very famous book by the reputed physicist, Erwin Schrödinger, of quantum mechanics fame it is titled What is Life?

Well, left to myself, I would assert, life is not made up of unique substance, living organisms have unique characteristics!

[InfiniteNow]

Every individual's definition will be different.

Maybe super clusters of galaxies moving in concert with one another could be considered life. For others, they might stick to the more basic plant/animal set. Just depends on the application and context of your definition.

What is it to you?

[orbsycli]

Life's the opposite of death.

[orbsycli]

I've found heaven in Vaginas.

[Mercedes Benzene]

Some characteristics of life:
-Has cells
-Converts energy
-Grows
-Reproduces

...all living things have at least those in common. If something is missing any one of those, it is certainly not living.

[CraigD]

In considering the borderline cases of what is, in a conventional biological sense, alive and what is not, let’s not forget prions.

If answering the live-or-not question for viruses, which are unable to reproduce without using host cells, is difficult, answering it for prions, which appear to altogether lack nucleic acids, is even more so.

Personally, I suspect that a black-and-white distinction between living and unliving will prove increasingly unuseful as knowledge about both molecular biology and the organization of non-biological systems increases.

[infamous]

Originally Posted by someguy

Not knowing much about biology, I was wondering what makes something considerd to be alive?

Whether by chemical means or otherwise, life is: 'the ability to alter the enviormental conditions to sustain existence'.

Originally Posted by someguy

At what level is life considered to be there? Is a virus a life form? Bacteria?

It used to be common thought for science to consider a virus a nonliving entity. That view has slowly been changing over the last few years to the point where a few scientists believe that the virus may be a precursor to life.

Originally Posted by someguy

How much do we know about the makeup of life? DNA?
Thanks,
Some Guy

Actually, we have considerable knowledge about the structure of DNA at present. However, we still have much to learn about what subtle changes in this code have to do with the functionality of the organism.....................Infy

[Jay-qu]

Its going to be a tough question no matter where you slice it, I read an article about a group trying to create artificial life, they where given a few criteria that it had to meet: eat, grow, reproduce and evolve.