Where does life originate from?

[relativityfan]

hi,

can we say that life comes essentially from DNA and the resulting proteins?, but it can nly be developed in the right environemental conditions?
thank you for your reply

 

[Borek]

Your question is so ambiguous it is difficult to answer, please elaborate on what you really mean.

 

[relativityfan]

well, i just wonder if there is a merely chemical process leading to life, or if it is yet unknown by science. does science understand well now what chemical or biochemical processes lead to life and why? because cells are still very different than molecules. Can we say that cells are just a logical combination of molecules that is fully understood, is it merely a chemical process or is there a mechanism that is missing by science?

i woud be very grateful for any reply!

 

[Borek]

There is no doubt that whatever happens in the cell is just a chemistry, but we are still far from knowing all details.

However, it is still not clear to me whether you ask about origin of life, or about the processes responsible for cell building and replication. In both cases the answer is the same - chemistry with blurry details

 

[relativityfan]

ok, but this still seems very mysterious for me. i wonder if there is no major component, from chemistry, that is missing? do you also believe that known chemistry(its known trends in structures and chemical reactions) is responsible of everything in biology?

 

[Phrak]

relativityfan. I think you should stop looking for mysterious components, and instead contemplate upon the magnitude of numbers with large exponents. In a few billions of years, among trillions upon trillions of organic molecules, what might ensue.

 

[relativityfan]

OK, so what is the source of life. is it RNA, DNA?

 

[bobze]

OK, so what is the source of life. is it RNA, DNA?

I think what Borek was getting at RF, was "source" is ambiguous. Can you define what you mean?

 

[Borek]

Define "source of life".

Edit: that what happens when you uplink gets slow, bobze posted while I was waiting for refresh.

 

[bobze]

Define "source of life".

Edit: that what happens when you uplink gets slow, bobze posted while I was waiting for refresh.

 

[relativityfan]

I mean by source the most basic molecule or structure that makes a difference between chemistry and biology

 

[Borek]

That's quite unusual use of the word "source".

No such thing.

No single molecule can be treated as alive. Perhaps the closest to the simplest possible structures that can be treated as alive are some small viruses, but in a way they are not alive on their own, they need to infect a living cell to replicate, as they rely on external (cellular) biochemistry to build own copies.

Problem is, border between life and non-life is blurry, there is a whole spectrum of objects between those clearly alive (like human) and those clearly inanimate (as a rock). Depending on how you define life, border moves, and things that are alive according to one definition, can be inanimate according to other definition.

 

[granpa]

to be alive something must be able to reproduce and also able to evolve.
look up rna world hypothesis

 

[minorwork]

to be alive something must be able to reproduce and also able to evolve.
look up rna world hypothesis

I'm something but I guess I must be dead. I can't reproduce. Mules must be dead too.

Tuff to define life, it is. Is there life on Mars? What would qualify? What does it mean to say something is alive as distinguished from it being dead? You'll only find a priori answers that don't exist empirically. No big deal. Just choose the relevant to the problem definition.

 

[granpa]

I certainly hope that was a joke.
I was, of course, referring to species not individuals

in some rare cases it may be hard to say exactly where one species ends and another begins but that doesn't change anything.
http://en.wikipedia.org/wiki/Ring_species

 

[Nienstien]

Just to clarify there is no standard model of the origin of life yet. Free to be discovered.

 

[minorwork]

I certainly hope that was a joke.
I was, of course, referring to species not individuals

in some rare cases it may be hard to say exactly where one species ends and another begins but that doesn't change anything.
http://en.wikipedia.org/wiki/Ring_species

I was hoping YOU were joking or just imprecise. And now your claim is that only species possesses life. Not individuals. Your imprecision continues.

 

[madcat8000]

I think the simpleist example of life would be to say a living organism takes advantage of disequilbrium in its environment to gather energy, copy itself, and has some "semi-stable" way to store heritable information, that is to say that the information about itself is generaly stable but has a factor that can allow it to change. It definitvely doesn't have to have DNA nor a Carbon structer. Might even be a machine.

 

[granpa]

oh. I see that you are joking.

 

[LivaN]

to be alive something must be able to reproduce and also able to evolve.
look up rna world hypothesis

Don't species evolve? Can an individual evolve?
If every human suddenly died except for myself, would I be able to reproduce? Would I be able to evolve? Am I still alive?

Surely a scientist could hypotheticaly create an organism with a brain and nervous system that has no possible way to reproduce. Would this organism be alive?

If a machine is created (year 4041?) , that has an artificial brain that is equivilant of a humans. This machine is self aware, can never die, cannot procreate, is it alive?

Your definition of what is alive is flawed!

 

[madcat8000]

Nein it is only the potential for reproduction and evolutionary differention that matters. The last man on Earth has the potential for reproduction just not the ability. Still alive. The self aware computer that has no internal ability to reproduce may be a valued member of society but is not alive.

 

[LivaN]

Nein it is only the potential for reproduction and evolutionary differention that matters. The last man on Earth has the potential for reproduction just not the ability. Still alive. The self aware computer that has no internal ability to reproduce may be a valued member of society but is not alive.

So a synthesized biological entity that is for all intensive purposes the identical of anyone one biological entity on earth, aside from its lack of ability to procreate, is by your definition not alive?

So if your dna was sampled and used to create a copy of you, with all your potential for procreation removed from the copy...would it be alive? It is then given your memories (it is the year 4041 after all). Is it still not alive? If someone were to destroy this copy of you, would it be murder? How can it be if it is not alive?

I'm sorry, but being self aware is grounds for being alive. Everything that is self aware is alive. Period.

 

[Borek]

10 posts ago I wrote that there is no one widely accepted definition of what is alive and what life is. Beat it as long as you want (biologists do it for decades), you will not get to any better conclusion that you agree to disagree.

 

[madcat8000]

You seem to be confuseing your personal morality with scientific fact. Self awareness only means that it qualifies as an individual. Give it all the rights and respect you want, can't make it a lifeform. And there fore not alive.

 

[LivaN]

10 posts ago I wrote that there is no one widely accepted definition of what is alive and what life is. Beat it as long as you want (biologists do it for decades), you will not get to any better conclusion that you agree to disagree.

I think you're right.

I can't however imagine any definition, of what is alive, leaving out self awareness as a garentee of being alive.

 

[bobze]

10 posts ago I wrote that there is no one widely accepted definition of what is alive and what life is. Beat it as long as you want (biologists do it for decades), you will not get to any better conclusion that you agree to disagree.

Good posts Borek.

There isn't a "natural" definition of life, no "law" of life.

Life is a human imposed definition on nature, we need such a definition to have meaningful discourse on life but that doesn't mean scientists don't understand the limitations of the definition (an an important aspect of defining anything in science is to understand it's limitations).

Biologists typically roll out a definition of life that looks something like;

1. Capable of reproducing with fidelity
2. Capable of converting energy from one form to another
3. Capable of dealing with metabolic waste
4. The cell is the smallest unit
5. Capable of biological evolution

Of course, this means that many "organisms" would fall into a shades of gray kind of deal where our definition of life is concerned. Like certain Mycobacteriums, Chlamydia or viruses.

Probably the most "simple", accurate and inclusive definition of life we could come up with is something capable of evolution (specifically by natural selection as NS is required for adaptive evolution).

 

[LivaN]

You seem to be confuseing your personal morality with scientific fact.

No, just trying to make logical sense of the term alive, and the context it's used in daily.

Self awareness only means that it qualifies as an individual. Give it all the rights and respect you want, can't make it a lifeform. And there fore not alive.

My bad, I should have left out the murder thing.


So you could exist without being alive? Interesting angle.

But then, could I argue that my mental processes be included in your definition?

takes advantage of disequilbrium in its environment to gather energy, copy itself, and has some "semi-stable" way to store heritable information, that is to say that the information about itself is generaly stable but has a factor that can allow it to change.

To a good degree, my mental processes follow your definition. They take advantage of the environmet (grey matter), they propagate, I am stable but overtime my mental processes "evolve"...would that work?

 

[granpa]

So a synthesized biological entity that is for all intensive purposes the identical of anyone one biological entity on earth, aside from its lack of ability to procreate, is by your definition not alive?
.

but it can procreate by synthesizing another.
That makes it a member of a species that is by definition 'alive' and therefore it is 'alive' too.

Nobody said procreation had to be done biologically.

 

[LivaN]

but it can procreate by synthesizing another.
Nobody said it had to be done biologically.

If the biological entity were say a mouse, then it couldn't. Well not by itself. It would need the scientist that created it to create more!

I think we are going about the definition differnetly. You look at what the definition currently appleis to, ie all life on earth, and then are trying to draw in the similarities to derive a definition.

I'm looking at the intended meaning of the word "alive" and then trying to define the meaning. I think it is more the "intention" that should determine if something is alive.

Two organisms (cats?) standing next to each other. One has the potential to procreate. The other does not and never will. Bother are otherwise identical. I just cannot logically conclude that one is alive and the other is not.
If I did, then to me "alive" is somewhat the equivilant of "replication", in which case there must be another word to define the similarity of the cats with respect to two stone cats.

 

[Siv]

The line between living and non-living is not as clear cut as we think it is. Life is the label we give to a certain type of complexity which involves replication.
Its a spectrum, really.
Viruses are actually in the fuzzy middle, its hard for people to categorize them clearly either way.